代码

#include <stdio.h>
#define SIZE (200 << (20 - 2))

int A[SIZE];

void sort(unsigned *a, int n){
#define N 50000000
#define D 256
#define D1 255
#define cal(w,w2,tw,op) \
p=w2-1;\
for(i=0;i<D;++i)rs[i]=p,p+=tw[i];\
for(i=0;i<N;i+=8){\
	p=w+i;\
	*++rs[p[0]op]=p[0],\
	*++rs[p[1]op]=p[1],\
	*++rs[p[2]op]=p[2],\
	*++rs[p[3]op]=p[3],\
	*++rs[p[4]op]=p[4],\
	*++rs[p[5]op]=p[5],\
	*++rs[p[6]op]=p[6],\
	*++rs[p[7]op]=p[7];\
}
unsigned b[N],*rs[D],t0[D],t1[D],t2[D],t3[D];
unsigned*p,i,x;

for(i=0;i<N;){
#define A x=a[i],++t0[x&D1],++t1[x>>8&D1],++t2[x>>16&D1],++t3[x>>24],++i;
A A A A A A A A 
#undef A
}
cal(a,b,t0,&D1);
cal(b,a,t1,>>8&D1);
cal(a,b,t2,>>16&D1);
cal(b,a,t3,>>24);
}

int main() {
	for (int i = 0; i < SIZE; i++) {
		A[i] = i ^ (i >> 5);
	}
	sort((unsigned *) A, 50000000);
	printf("%d\n", A[0]);
}

评测结果