代码

#include <stdio.h>
#include <string.h>

void sort(unsigned * a, int n) {
	static int cnt[256];
	static unsigned b[100000005];
	for (int i = 0; i < 32; i += 8) {
		memset(cnt, 0, 1024);
		for (int j = 0; j < n; j += 4) {
			cnt[a[j] >> i & 255] ++;
			cnt[a[j] >> i + 1 & 255] ++;
			cnt[a[j] >> i + 2 & 255] ++;
			cnt[a[j] >> i + 3 & 255] ++;
		}
		for (int j = 1; j < 256; ++ j) {
			cnt[j] += cnt[j - 1];
		}
		for (int j = n - 1; ~j; -- j) {
			b[-- cnt[a[j] >> i & 255]] = a[j];
		}
		memcpy(a, b, sizeof(unsigned) * n);
	}
}

评测结果