代码

unsigned b[10005];

int s1[260], s2[260], s3[260], s4[260];

void sort(unsigned *a, int n)
{
	for(register int i = 0; i < n; i ++)
	{
		s1[a[i] & 255] ++, s2[(a[i] >> 8) & 255] ++;
		s3[(a[i] >> 16) & 255] ++, s4[a[i] >> 24] ++;
	}
	for(register int i = 1; i < 256; i ++) 
		s1[i] += s1[i - 1];
	for(register int i = 1; i < 256; i ++) 
		s2[i] += s2[i - 1];
	for(register int i = 1; i < 256; i ++) 
		s3[i] += s3[i - 1];
	for(register int i = 1; i < 256; i ++) 
		s4[i] += s4[i - 1];
	for(register int i = n - 1; ~ i; i --)
		b[-- s1[a[i] & 255]] = a[i];
	for(register int i = n - 1; ~ i; i --)
		a[-- s2[(b[i] >> 8) & 255]] = b[i];
	for(register int i = n - 1; ~ i; i --)
		b[-- s3[(a[i] >> 16) & 255]] = a[i];
	for(register int i = n - 1; ~ i; i --)
		a[-- s4[b[i] >> 24]] = b[i];
}

评测结果