代码

#include <algorithm>
namespace Radix_Sort{
const int B=16,M=(1<<B)-1,N=100000000,W=32;
int cnt[1<<B],t[N];
template<typename T=int>inline void radix_sort(T*_begin_iter,T*_end_iter){
	int n=_end_iter-_begin_iter;
	int*b=t;
	for(int i=0;i<W;i+=B){
		for(int j=0;j<=M;j++)cnt[j]=0;
		for(int j=0;j<n;j++)++cnt[(_begin_iter[j]>>i)&M];
		for(int s=0,j=0;j<=M;j++)s+=cnt[j],cnt[j]=s-cnt[j];
		for(int j=0;j<n;j++)b[cnt[(_begin_iter[j]>>i)&M]++]=_begin_iter[j];
		swap(_begin_iter,b);
	}
}
}
using Radix_Sort::radix_sort;
void sort(unsigned *a, int n) {
	radix_sort<unsigned>(a, a + n);
}

评测结果