代码

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
const int N = 2e8 + 10, M = 256;

unsigned b[N];
int d[M];

void sort(unsigned *a, int n){
    for(int i = 0; i < 4; i ++ ){
        int t = i << 3;
        for(int j = 0; j < M; j ++ ) d[j] = 0;
        for(int j = 0; j < n; j ++ ) d[a[j] >> t & M - 1] ++ ;
        for(int j = 1; j < M; j ++ ) d[j] += d[j - 1];
        for(int j = n - 1; j >= 0; j -- ) b[ -- d[a[j] >> t & M - 1]] = a[j];
        memcpy(a, b, sizeof(int) * n);
    }
}

评测结果