fix comments

Author: yosupo06

atcoder/internal_bit.hpp

@@ -9,14 +9,15 @@ namespace atcoder {
 
 namespace internal {
 
+// @return same with std::bit::bit_ceil
 unsigned int bit_ceil(unsigned int n) {
     unsigned int x = 1;
     while (x < (unsigned int)(n)) x *= 2;
     return x;
 }
 
 // @param n `1 <= n`
-// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
+// @return same with std::bit::countr_zero
 int countr_zero(unsigned int n) {
 #ifdef _MSC_VER
     unsigned long index;
@@ -28,7 +29,7 @@ int countr_zero(unsigned int n) {
 }
 
 // @param n `1 <= n`
-// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
+// @return same with std::bit::countr_zero
 constexpr int countr_zero_constexpr(unsigned int n) {
     int x = 0;
     while (!(n & (1 << x))) x++;

test/unittest/bit_test.cpp

@@ -19,9 +19,10 @@ TEST(BitTest, BitCeil) {
     ASSERT_EQ(8, internal::bit_ceil(7U));
     ASSERT_EQ(8, internal::bit_ceil(8U));
     ASSERT_EQ(16, internal::bit_ceil(9U));
-    ASSERT_EQ(1U<<30, internal::bit_ceil(1U << 30));
-    ASSERT_EQ(1U<<31, internal::bit_ceil((1U << 30) + 1));
-    ASSERT_EQ(1U<<31, internal::bit_ceil((1U << 31) - 1));
+    ASSERT_EQ(1U << 30, internal::bit_ceil(1U << 30));
+    ASSERT_EQ(1U << 31, internal::bit_ceil((1U << 30) + 1));
+    ASSERT_EQ(1U << 31, internal::bit_ceil((1U << 31) - 1));
+    ASSERT_EQ(1U << 31, internal::bit_ceil(1U << 31));
 }
 
 TEST(BitTest, CountrZero) {