代码

#include <cstring>
void sort(unsigned *a, int n) {
    static unsigned cnt[65536]; static unsigned tmp[1<<16];
    unsigned *src=a,*dst=tmp;
    for(int pass=0;pass<2;pass++){
        memset(cnt,0,sizeof(cnt)); int sh=pass*16;
        for(int i=0;i<n;i++) cnt[(src[i]>>sh)&65535]++;
        unsigned s=0; for(int i=0;i<65536;i++){unsigned c=cnt[i];cnt[i]=s;s+=c;}
        for(int i=0;i<n;i++) dst[cnt[(src[i]>>sh)&65535]++]=src[i];
        unsigned*t=src;src=dst;dst=t;
    }
    if(src!=a) memcpy(a,src,n*4);
}

评测结果