代码

#include <cstdio>
#include <algorithm>

int d[10];

// lexicographical_order: 11.888 ms / 59.242 ms
void lexicographical_order(const int size)
{
    int tot = 1, i, j;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1;
    // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    while (--tot)
    {
        i = size - 2;
        while (d[i] > d[i+1]) i--;
        j = size - 1;
        while (j != i) {
            if (d[j] > d[i]) {
                std::swap(d[j], d[i]);
                break;
            } else j--;
        }
        i++;
        j = size - 1;
        while (i < j) {
            std::swap(d[i], d[j]);
            i++; j--;
        }
        // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    }
}

// incremental_way: 87.111 ms / 60.427 ms
void incremental_way(const int size)
{
    int p[10], tot = 1, i, j, k, l;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1, p[i] = tot;
    tot = 0;
    // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    while (++tot < p[size-1])
    {
        i = 0;
        while (tot % p[i+1] == 0) i++;
        j = 0;
        k = 0;
        for (j = 0; j < size; j++) {
            if (d[j] <= i+1) {
                d[j] = i+2 - d[j];
                k = j;
            } else if (d[j] == i+2) {
                std::swap(d[j], d[k]);
            }
        }
        // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    }
}

// decremental_way: 5.057 ms / 58.64 ms 
void decremental_way(const int size)
{
    int tot = 1, i, j, k, l;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1;
    k = size - 1;
    // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    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 (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    }
}

// neighbor_swap: ? ms / 41.727ms
void neighbor_swap(const int size)
{
    bool r[10];
    int pre[11], nxt[11];
    int tot = 1, i, j, k;
    for (i = 0; i < size; i++) r[i] = false, tot *= i+1;
    for (i = 1; i < size; i++) pre[i] = i-1; pre[0] = 10; nxt[10] = 0;
    for (i = 0; i < size-1; i++) nxt[i] = i+1; nxt[size-1] = 10; pre[10] = size-1;
    // i = 0; while (pre[i] != 10) i++; while (nxt[i] != 10) printf("%d ", i+1), i = nxt[i]; printf("%d\n", i+1);
    while (--tot)
    {
        i = size-1;
        while ((!r[i] && pre[i] > i) || (r[i] && nxt[i] > i)) {
            r[i--] ^= 1;
        }
        if (!r[i]) {
            j = pre[i];
            pre[i] = pre[j];
            pre[j] = nxt[pre[i]] = i;
            nxt[j] = nxt[i];
            nxt[i] = pre[nxt[j]] = j;
        } else {
            j = nxt[i];
            nxt[i] = nxt[j];
            nxt[j] = pre[nxt[i]] = i;
            pre[j] = pre[i];
            pre[i] = nxt[pre[j]] = j;
        }
        // i = 0; while (pre[i] != 10) i++; while (nxt[i] != 10) printf("%d ", i+1), i = nxt[i]; printf("%d\n", i+1);
    }
}

// blank: ? ms / 57.307 ms
void blank(const int size)
{
    int tot = 1, i;
    for (i = 0; i < size; i++) d[i] = i+1, tot *= i+1;
    while (tot--) {
        // for (i = 0; i < size-1; i++) printf("%d ", d[i]); printf("%d\n", d[i]);
    }
}

int main()
{
    // blank(10);
    // lexicographical_order(10);
    // incremental_way(10);
    // decremental_way(10);
    neighbor_swap(10);
    return 0;
}

评测结果