poj 2531

暴力搜索 因为数据太弱 并不想去加什么剪枝

#include <iostream>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;

#define met(a, b) memset(a, b, sizeof(a))

const int N = 25;

int g[N][N], vis[N], n, ans;

void dfs (int k, int sum);

int main ()
{
    while (cin >> n)
    {
        for (int i=0; i<n; i++)
            for (int j=0; j<n; j++)
                cin >> g[i][j];

        ans = 0;
        met (vis, 0);
        vis[0] = 1;
        dfs (0, 0);
        cout << ans << endl;
    }
    return 0;
}

void dfs (int k, int sum)
{
    int x = sum;
    for (int i=0; i<n; i++)
    {
        if (vis[i]) x -= g[k][i];
        else x += g[k][i];
    }
    if (x > ans) ans = x;

    for (int i=k+1; i<n; i++)
    {
        if (!vis[i])
        {
            vis[i] = 1;
            dfs (i, x);
            vis[i] = 0;
        }
    }
}