传送门

下标为1写法

#include <bits/stdc++.h>
using namespace std;
typedef long long i64;
typedef pair<int, int> PII;

const int N = 21;
int f[1 << N][N];
int n;
int w[N][N];

int main()
{
    ios::sync_with_stdio(false); cin.tie(0);

    cin >> n;
    for (int i = 1; i <= n; i ++) 
        for (int j = 1; j <= n; j ++)
            cin >> w[i][j];

    memset(f, 0x3f, sizeof f);
    f[1][1] = 0;

    for (int i = 1; i < 1 << n; i ++)
        for (int j = 1; j <= n; j ++)
            for (int k = 1; k <= n; k ++)
                if (!(i & (1 << (k - 1))))
                    f[i | (1 << (k - 1))][k] = min(f[i | (1 << (k - 1))][k], f[i][j] + w[j][k]);

    cout << f[(1 << n) - 1][n] << "\n";


    return 0;
}

下标为0写法

#include <bits/stdc++.h>
using namespace std;
typedef long long i64;
typedef pair<int, int> PII;

const int N = 21;
int f[1 << N][N];
int w[N][N];
int n;

int main()
{
    ios::sync_with_stdio(false); cin.tie(0);

    cin >> n;
    for (int i = 0; i < n; i ++)
        for (int j = 0; j < n; j ++)
            cin >> w[i][j];

    memset(f, 0x3f, sizeof f);
    f[1][0] = 0;

    //下面是关键模板
    for (int i = 1; i < 1 << n; i ++)
        for (int j = 0; j < n; j ++)  //当前走到第j个点
            if (f[i][j] < (1 << 30)) //可省略
                for (int k = 0; k < n; k ++)  //枚举与j相连的状态
                    if (!(i & (1 << k)))
                        f[i + (1 << k)][k] = min(f[i + (1 << k)][k], f[i][j] + w[j][k]);

    cout << f[(1 << n) - 1][n - 1] << "\n";

    return 0;
}