代码

unsigned b1[256], b2[256], b3[256], b4[256], c[100000005];
void sort(unsigned *a, int n) {
	for (int i = 0; i < n; ++i) {
		++b1[a[i] & 255]; ++b2[a[i] >> 8 & 255];
		++b3[a[i] >> 16 & 255]; ++b4[a[i] >> 24 & 255];
	}
	for (int i = 1; i < 256; ++i) {
		b1[i] += b1[i - 1]; b2[i] += b2[i - 1];
		b3[i] += b3[i - 1]; b4[i] += b4[i - 1];
	}
	for (int i = n - 1; i >= 0; --i) c[--b1[a[i] & 255]] = a[i];
	for (int i = n - 1; i >= 0; --i) a[--b2[c[i] >> 8 & 255]] = c[i];
	for (int i = n - 1; i >= 0; --i) c[--b3[a[i] >> 16 & 255]] = a[i];
	for (int i = n - 1; i >= 0; --i) a[--b4[c[i] >> 24 & 255]] = c[i];
}

评测结果