代码

#include <cstdio>
#include <algorithm>

int d[11];

// decremental_way: 51.146 ms / 421.106 ms 
void decremental_way(const int size)
{
    int tot = 1, i, j, k, l, *pi, *pk = d+size-1, *pe = d+size-1;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1;
    for (pi = d; pi != pe; pi++) printf("%d ", *pi); printf("%d\n", *pe);
    while (--tot)
    {
        i = 0; while (d[i] + i == size) i++;
        if (i) {
            j = i; pi = d+(j-i); 
            while (j < size) {
                if (d[j] == size-i) *pi = *(pi-1), *(pi-1) = d[j]; else *pi = d[j];
                j++; pi++;
            }
            j = i; while (j) d[size-j] = size-j+1, j--;
            pk = d + size - 1;
        } else {
            std::swap(*pk, *(pk-1));
            pk--;
        }
        for (pi = d; pi != pe; pi++) printf("%d ", *pi); printf("%d\n", *pe);
    }
}

int main()
{
    // decremental_way(5);
    decremental_way(9);
    // decremental_way(11);
    return 0;
}

评测结果