代码

#include <cstdio>
#include <algorithm>

int d[11];

// decremental_way: ? ms / ? ms 
void decremental_way(const int size)
{
    int tot = 1, i, j, k, l, *pi, *pe = d+size-1;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1;
    k = size - 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; while (j < size) {
                if (d[j] == size-i) d[j-i] = d[j-i-1], d[j-i-1] = d[j]; else d[j-i] = d[j];
                j++;
            }
            j = i; while (j) d[size-j] = size-j+1, j--;
            k = size - 1;
        } else {
            std::swap(d[k], d[k-1]);
            k--;
        }
        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