状态压缩DP

状态压缩DP

一、集合类

1. 最短Hamilton路径

#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;

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

int main()
{
    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;
    for(int i = 2; i < 1 << n; i++)
        for(int j = 0; j < n; j++)
        {
            if(i >> j & 1)
            {
                for(int k = 0; k < n; k++)
                {
                    if(i - (1 << j) >> k & 1)
                        f[i][j] = min(f[i][j], f[i - (1 << j)][k] + w[k][j]);
                }
            }
        }
    cout << f[(1 << n) - 1][n - 1] << endl;
    return 0;
}