代码

#include <algorithm>

unsigned b[200000000];
unsigned buc[2][65536];

void sort(unsigned *a, int n)
{
    for (int i = 0; i < n; ++i)
    {
        ++buc[0][a[i] & 65535];
        ++buc[1][a[i] >> 16];
    }
    for (unsigned k = 0; k < 2; ++k)
    {
        unsigned offset = 0;
        for (unsigned i = 0; i < 65536; ++i) 
            std::swap(buc[k][i], offset), offset += buc[k][i];
    }
    for (unsigned i = 0; i < n; ++i) b[buc[0][a[i] & 65535]++] = a[i];
    for (unsigned i = 0; i < n; ++i) a[buc[1][b[i] >> 16]++] = b[i];
}

评测结果