POJ 2907

题意：平面上给你n个点。1为起始点，问你从1号点出发经过其他所有点再回到1号点的最短距离，两点之间的距离是曼哈顿距离（abs（x1-x2）+abs(y1-y2)）。

思路：DFS，算出每次的距离，取最短即可。

#include<cmath>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#define INF 0x7fffffff
using namespace std;
typedef struct POS{
    int x, y;
    int dist(const POS &A){
        return abs(x-A.x) + abs(y-A.y); 
    }
}Node;
Node node[11], start;
int vis[11], ans, N;
void dfs(int dep, int len, Node tmp){
    if(dep == N){
        ans = min(ans, len+tmp.dist(start));
        return ;
    }
    for(int i = 0;i < N;i ++){
        if(!vis[i]){
            vis[i] = 1;
            dfs(dep+1, len+tmp.dist(node[i]), node[i]);
            vis[i] = 0;
        }
    }
}
int main(){
    int t, n, m;
    /* freopen("in.c", "r", stdin); */
    scanf("%d", &t);
    while(t--){
        scanf("%d%d", &n, &m);
        scanf("%d%d", &start.x, &start.y);
        scanf("%d", &N);
        for(int i = 0;i < N;i ++) scanf("%d%d", &node[i].x, &node[i].y);
        ans = INF;
        dfs(0, 0, start);
        printf("The shortest path has length %d\n", ans);
    }
    return 0;
}