代码

#include <algorithm>

typedef unsigned int uint;

void sort(uint *a, int n) {
	uint t[100000000];
	register uint b0[256], b1[256], b2[256], b3[256];
	std::fill(t, t + 256, 0);
	std::fill(b0, b0 + 256, 0);
	std::fill(b1, b1 + 256, 0);
	std::fill(b2, b2 + 256, 0);
	std::fill(b3, b3 + 256, 0);
	for (register int i = 0; i < n; i++) {
		b0[a[i] & 255]++;
		b1[(a[i] >> 8) & 255]++;
		b2[(a[i] >> 16) & 255]++;
		b3[(a[i] >> 24) & 255]++;
	}
	for (register int i = 0; i < 256; i++) {
		b0[i] += b0[i - 1];
		b1[i] += b1[i - 1];
		b2[i] += b2[i - 1];
		b3[i] += b3[i - 1];
	}
	for (register int i = n - 1; ~i; i--) {
		t[--b0[a[i] & 255]] = a[i];
	}
	for (register int i = n - 1; ~i; i--) {
		a[--b1[(t[i] >> 8) & 255]] = t[i];
	}
	for (register int i = n - 1; ~i; i--) {
		t[--b2[(a[i] >> 16) & 255]] = a[i];
	}
	for (register int i = n - 1; ~i; i--) {
		a[--b3[(t[i] >> 24) & 255]] = t[i];
	}
}

评测结果