replace bit_ceil

Author: yosupo06

atcoder/internal_bit.hpp

@@ -5,17 +5,29 @@
 #include <intrin.h>
 #endif
 
+#if __cplusplus >= 202002L
+#include <bit>
+#endif
+
 namespace atcoder {
 
 namespace internal {
 
+#if __cplusplus >= 202002L
+
+using std::bit_ceil;
+
+#else
+
 // @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;
 }
 
+#endif
+
 // @param n `1 <= n`
 // @return same with std::bit::countr_zero
 int countr_zero(unsigned int n) {