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beston123beston123
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算法
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src/main/java/code/algorithm/wordcount/WordCountMain.java renamed to src/main/java/code/algorithm/divideconquer/WordCountMain.java

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package code.algorithm.wordcount;
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package code.algorithm.divideconquer;
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import code.collection.MinHeap;
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import code.collection.MinArray;
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/**
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* 〈WorkCount〉<p>
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* 〈功能详细描述〉
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* MapReduce，分治算法
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*
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* @author zixiao
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* @date 2019/2/21

src/main/java/code/algorithm/ConsistentHash.java renamed to src/main/java/code/algorithm/hash/ConsistentHash.java

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package code.algorithm;
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package code.algorithm.hash;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;

‎src/main/java/code/algorithm/hash/MurmurHash.java‎

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package code.algorithm.hash;
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/**
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*  MurMurHash算法，是非加密HASH算法，性能很高，
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*  比传统的CRC32,MD5，SHA-1（这两个算法都是加密HASH算法，复杂度本身就很高，带来的性能上的损害也不可避免）
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*  等HASH算法要快很多，而且据说这个算法的碰撞率很低.
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*  http://murmurhash.googlepages.com/
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*
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* @author zixiao
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* @date 2019/11/28
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*/
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public final class MurmurHash {
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// all methods static; private constructor.
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private MurmurHash() {}
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/**
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* Generates 32 bit hash from byte array of the given length and
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* seed.
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*
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* @param data byte array to hash
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* @param length length of the array to hash
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* @param seed initial seed value
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* @return 32 bit hash of the given array
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*/
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public static int hash32(final byte[] data, int length, int seed) {
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// 'm' and 'r' are mixing constants generated offline.
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// They're not really 'magic', they just happen to work well.
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final int m = 0x5bd1e995;
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final int r = 24;
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// Initialize the hash to a random value
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int h = seed^length;
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int length4 = length/4;
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for (int i=0; i<length4; i++) {
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final int i4 = i*4;
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int k = (data[i4+0]&0xff) +((data[i4+1]&0xff)<<8)
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+((data[i4+2]&0xff)<<16) +((data[i4+3]&0xff)<<24);
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k *= m;
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k ^= k >>> r;
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k *= m;
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h *= m;
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h ^= k;
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}
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// Handle the last few bytes of the input array
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switch (length%4) {
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case 3: h ^= (data[(length&~3) +2]&0xff) << 16;
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case 2: h ^= (data[(length&~3) +1]&0xff) << 8;
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case 1: h ^= (data[length&~3]&0xff);
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h *= m;
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}
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h ^= h >>> 13;
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h *= m;
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h ^= h >>> 15;
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return h;
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}
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/**
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* Generates 32 bit hash from byte array with default seed value.
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*
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* @param data byte array to hash
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* @param length length of the array to hash
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* @return 32 bit hash of the given array
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*/
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public static int hash32(final byte[] data, int length) {
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return hash32(data, length, 0x9747b28c);
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}
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/**
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* Generates 32 bit hash from a string.
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*
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* @param text string to hash
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* @return 32 bit hash of the given string
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*/
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public static int hash32(final String text) {
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final byte[] bytes = text.getBytes();
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return hash32(bytes, bytes.length);
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}
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/**
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* Generates 32 bit hash from a substring.
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*
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* @param text string to hash
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* @param from starting index
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* @param length length of the substring to hash
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* @return 32 bit hash of the given string
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*/
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public static int hash32(final String text, int from, int length) {
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return hash32(text.substring( from, from+length));
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}
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/**
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* Generates 64 bit hash from byte array of the given length and seed.
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*
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* @param data byte array to hash
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* @param length length of the array to hash
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* @param seed initial seed value
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* @return 64 bit hash of the given array
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*/
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public static long hash64(final byte[] data, int length, int seed) {
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final long m = 0xc6a4a7935bd1e995L;
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final int r = 47;
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long h = (seed&0xffffffffl)^(length*m);
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int length8 = length/8;
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for (int i=0; i<length8; i++) {
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final int i8 = i*8;
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long k = ((long)data[i8+0]&0xff) +(((long)data[i8+1]&0xff)<<8)
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+(((long)data[i8+2]&0xff)<<16) +(((long)data[i8+3]&0xff)<<24)
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+(((long)data[i8+4]&0xff)<<32) +(((long)data[i8+5]&0xff)<<40)
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+(((long)data[i8+6]&0xff)<<48) +(((long)data[i8+7]&0xff)<<56);
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k *= m;
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k ^= k >>> r;
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k *= m;
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h ^= k;
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h *= m;
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}
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switch (length%8) {
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case 7: h ^= (long)(data[(length&~7)+6]&0xff) << 48;
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case 6: h ^= (long)(data[(length&~7)+5]&0xff) << 40;
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case 5: h ^= (long)(data[(length&~7)+4]&0xff) << 32;
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case 4: h ^= (long)(data[(length&~7)+3]&0xff) << 24;
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case 3: h ^= (long)(data[(length&~7)+2]&0xff) << 16;
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case 2: h ^= (long)(data[(length&~7)+1]&0xff) << 8;
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case 1: h ^= (long)(data[length&~7]&0xff);
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h *= m;
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};
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h ^= h >>> r;
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h *= m;
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h ^= h >>> r;
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return h;
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}
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/**
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* Generates 64 bit hash from byte array with default seed value.
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*
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* @param data byte array to hash
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* @param length length of the array to hash
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* @return 64 bit hash of the given string
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*/
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public static long hash64(final byte[] data, int length) {
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return hash64(data, length, 0xe17a1465);
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}
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/**
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* Generates 64 bit hash from a string.
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*
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* @param text string to hash
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* @return 64 bit hash of the given string
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*/
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public static long hash64(final String text) {
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final byte[] bytes = text.getBytes();
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return hash64(bytes, bytes.length);
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}
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/**
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* Generates 64 bit hash from a substring.
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*
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* @param text string to hash
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* @param from starting index
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* @param length length of the substring to hash
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* @return 64 bit hash of the given array
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*/
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public static long hash64(final String text, int from, int length) {
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return hash64(text.substring( from, from+length));
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}
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}

‎src/main/java/code/algorithm/hash/PasswordEncrypt.java‎

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package code.algorithm.hash;
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import code.collection.hashtable.HashMap;
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import code.util.Encrypt;
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import lombok.AllArgsConstructor;
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import lombok.Data;
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import java.io.Serializable;
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import java.util.UUID;
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/**
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* 〈密码加密〉<p>
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* sha256(md5(password) + slat)
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*
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* @author zixiao
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* @date 2019/12/10
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*/
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public class PasswordEncrypt {
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private static HashMap<String, UserLogin> userLoginTable = new HashMap<>();
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@Data
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@AllArgsConstructor
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class UserLogin implements Serializable {
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String password;
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String slat;
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}
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public boolean register(String userName, String password){
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if(userLoginTable.contains(userName)){
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return false;
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}
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userLoginTable.put(userName, register(password));
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return true;
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}
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private UserLogin register(String password){
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String slat = UUID.randomUUID().toString().substring(0, 8);
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String pwd = Encrypt.encrypt(password, slat);
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System.out.println("加密password："+pwd + "，size:"+pwd.length());
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return new UserLogin(pwd, slat);
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}
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public boolean login(String userName, String password){
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UserLogin login = userLoginTable.get(userName);
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if(login == null){
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System.out.println("用户不存在");
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return false;
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}
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String pwd = Encrypt.encrypt(password, login.getSlat());
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if(pwd.equals(login.getPassword())){
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System.out.println("用户["+userName+"]登录成功");
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return true;
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}
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System.out.println("密码错误");
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return false;
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}
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public static void main(String[] args) {
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PasswordEncrypt encrypt = new PasswordEncrypt();
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encrypt.register("beston", "123456");
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encrypt.register("a", "z3lll39399440030sk2828000300e30d200309a9393er99392f9499lels");
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encrypt.register("b", "AAA"+System.currentTimeMillis());
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encrypt.register("c", UUID.randomUUID().toString());
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encrypt.login("beston", "123456");
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}
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}

‎src/main/java/code/algorithm/recall/EightQueen.java‎

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package code.algorithm.recall;
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/**
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* 〈8皇后问题〉<p>
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* 有一个8x8的棋盘，希望往里放8个棋子(皇后)，每个棋子所在的行、列、对角线都不能有另一个棋子
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*
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* @author zixiao
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* @date 2019/12/19
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*/
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public class EightQueen {
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private static int EIGHT = 8;
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/**
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* 下标索引代表行row
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* 值代表列col
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*/
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private int[] _8Queen = new int[EIGHT];
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public void build8Queen() {
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for (int i = 0; i < _8Queen.length; i++) {
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_8Queen[i] = -1;
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}
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calc8Queen(0);
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}
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private void calc8Queen(int row) {
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if (row == EIGHT) {
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print();
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return;
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}
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//8个列的位置可选
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for (int col = 0; col < EIGHT; col++) {
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if (isOk(row, col)) {
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_8Queen[row] = col;
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calc8Queen(row + 1);
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}
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}
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}
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/**
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* 与已放置的棋子，逐个比较
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* 1 不能同一列
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* 2 不能在对角线上
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*
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* @param row
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* @param col
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* @return
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*/
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private boolean isOk(int row, int col) {
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for (int i = 0; i < row; i++) {
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//在同一列，不符合要求
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if (_8Queen[i] == col) {
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return false;
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}
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//在对角线上，不符合要求
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if (Math.abs(_8Queen[i] - col) == Math.abs(i - row)) {
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return false;
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}
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}
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return true;
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}
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private void print() {
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StringBuilder sb = new StringBuilder();
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for (int i = 0; i < _8Queen.length; i++) {
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//第一行
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for (int j = 0; j < EIGHT; j++) {
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if (_8Queen[i] == j) {
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sb.append(1).append("\t");
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} else {
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sb.append(0).append("\t");
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}
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}
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sb.append("\n\r");
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}
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System.out.println(sb);
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}
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public static void main(String[] args) {
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EightQueen eightQueen = new EightQueen();
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eightQueen.build8Queen();
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}
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}

‎src/main/java/code/algorithm/recursion/Factorial.java‎

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package code.algorithm.recursion;
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/**
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* 〈阶乘〉<p>
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* 0!=1, 1!=1*0!, 2!=2*1!, 3!=3*2!, 4!=4*3!
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* 递归公式：f(n) = n * f(n-1), 终止条件：f(0) = 1
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*
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* @author zixiao
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* @date 2019/11/27
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*/
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public class Factorial {
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public static int f(int n) {
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if (n == 0) {
15+
return 1;
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}
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return n * f(n - 1);
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}
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public static void main(String[] args) {
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for (int i = 0; i < 10; i++) {
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System.out.println(i + "! = " + f(i));
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}
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}
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}

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