Add solution and test-cases for problem 2435

Author: 0xff-dev

leetcode/2401-2500/2435.Paths-in-Matrix-Whose-Sum-Is-Divisible-by-K/1.png

@@ -1,28 +1,41 @@
 # [2435.Paths in Matrix Whose Sum Is Divisible by K][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+You are given a **0-indexed** m x n integer matrix `grid` and an integer `k`. You are currently at position `(0, 0)` and you want to reach position `(m - 1, n - 1)` moving only **down** or **right**.
+
+Return the number of paths where the sum of the elements on the path is divisible by `k`. Since the answer may be very large, return it **modulo** `10^9 + 7`.
 
-**Example 1:**
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: grid = [[5,2,4],[3,0,5],[0,7,2]], k = 3
+Output: 2
+Explanation: There are two paths where the sum of the elements on the path is divisible by k.
+The first path highlighted in red has a sum of 5 + 2 + 4 + 5 + 2 = 18 which is divisible by 3.
+The second path highlighted in blue has a sum of 5 + 3 + 0 + 5 + 2 = 15 which is divisible by 3.
 ```
 
-## 题意
-> ...
+**Example 2:**  
 
-## 题解
+![2](./2.png)
 
-### 思路1
-> ...
-Paths in Matrix Whose Sum Is Divisible by K
-```go
+```
+Input: grid = [[0,0]], k = 5
+Output: 1
+Explanation: The path highlighted in red has a sum of 0 + 0 = 0 which is divisible by 5.
 ```
 
+**Example 3:**  
+
+![3](./3.png)
+
+```
+Input: grid = [[7,3,4,9],[2,3,6,2],[2,3,7,0]], k = 1
+Output: 10
+Explanation: Every integer is divisible by 1 so the sum of the elements on every possible path is divisible by k.
+```
 
 ## 结语
 

leetcode/2401-2500/2435.Paths-in-Matrix-Whose-Sum-Is-Divisible-by-K/2.png

@@ -1,5 +1,40 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+const mod2435 = 1000000007
+
+func Solution(grid [][]int, k int) int {
+	m, n := len(grid), len(grid[0])
+	dp := make([][][]int, m)
+	for i := 0; i < m; i++ {
+		dp[i] = make([][]int, n)
+		for j := 0; j < n; j++ {
+			dp[i][j] = make([]int, k)
+		}
+	}
+	sum := grid[0][0] % k
+	dp[0][0][sum] = 1
+
+	for idx := 1; idx < n; idx++ {
+		sum = (sum + grid[0][idx]) % k
+		dp[0][idx][sum] = 1
+	}
+
+	sum = grid[0][0] % k
+
+	// int first column
+	for idx := 1; idx < m; idx++ {
+		sum = (sum + grid[idx][0]) % k
+		dp[idx][0][sum] = 1
+	}
+
+	for i := 1; i < m; i++ {
+		for j := 1; j < n; j++ {
+			for idx := 0; idx < k; idx++ {
+				sum = (idx + grid[i][j]) % k
+				dp[i][j][sum] = (dp[i][j][sum] + dp[i-1][j][idx]) % mod2435
+				dp[i][j][sum] = (dp[i][j][sum] + dp[i][j-1][idx]) % mod2435
+			}
+		}
+	}
+	return dp[m-1][n-1][0]
 }

leetcode/2401-2500/2435.Paths-in-Matrix-Whose-Sum-Is-Divisible-by-K/3.png

@@ -10,30 +10,31 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs [][]int
+		k      int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", [][]int{{5, 2, 4}, {3, 0, 5}, {0, 7, 2}}, 3, 2},
+		{"TestCase2", [][]int{{0, 0}}, 5, 1},
+		{"TestCase3", [][]int{{7, 3, 4, 9}, {2, 3, 6, 2}, {2, 3, 7, 0}}, 1, 10},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.inputs, c.k)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",
+					c.expect, got, c.inputs, c.k)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }