代码

#include <algorithm>

const unsigned N  = (1 << 27) + 10, LB = 8, B = 1 << LB;
unsigned b[N];
unsigned cnt[B], *p[B], *pp;
void sort(unsigned *a, int n) {
--a;
	for(int k = 0; k < 32; k += LB) {
		for(int i = 1; i <= n; ++i)
			++cnt[a[i] >> k & (B - 1)];
		pp = b + 1;
		for(int i = 0; i < B; ++i)
			p[i] = pp, pp += cnt[i], cnt[i] = 0;
		for(int i = 1; i <= n; ++i)
			*p[a[i] >> k & (B - 1)]++ = a[i];
		k += LB;
		for(int i = 1; i <= n; ++i)
			++cnt[b[i] >> k & (B - 1)];
		pp = a + 1;
		for(int i = 0; i < B; ++i)
			p[i] = pp, pp += cnt[i], cnt[i] = 0;
		for(int i = 1; i <= n; ++i)
			*p[b[i] >> k & (B - 1)]++ = b[i];
	}
}

评测结果