代码

#include <bits/stdc++.h>
 
const int N = 1e8 + 7, maxv = 1 << 8;
 
void sort(unsigned int *a, int n) {
    unsigned int c1[maxv], c2[maxv], c3[maxv], c4[maxv], b[N];
    for (int i = 0; i < n; i++) {
        c1[a[i] & (maxv - 1)]++;
        c2[(a[i] >> 8) & (maxv - 1)]++;
        c3[(a[i] >> 16) & (maxv - 1)]++;
        c4[a[i] >> 24]++;
    }
    for (int i = 1; i < maxv; i++) c1[i] += c1[i - 1], c2[i] += c2[i - 1], c3[i] += c3[i - 1], c4[i] += c4[i - 1];
    for (int i = n - 1; i >= 0; i--) b[--c1[a[i] & (maxv - 1)]] = a[i];
    for (int i = n - 1; i >= 0; i--) a[--c2[(b[i] >> 8) & (maxv - 1)]] = b[i];
    for (int i = n - 1; i >= 0; i--) b[--c3[(a[i] >> 16) & (maxv - 1)]] = a[i];
    for (int i = n - 1; i >= 0; i--) a[--c4[b[i] >> 24]] = b[i];
}

评测结果