hdu 4568（状态压缩dp）

题意：一张n*m的网格内每个点有话费，还有若干个宝藏，问一个人要走进去拿走所有宝藏在走出来的最小花费。

思路：看宝藏只有13个直接想到了状压dp[i][j]拿了哪几个前一个为j的最小花费，先bfs+优先队列预处理出最短路，然后记忆化搜索就可。

代码如下：

/**************************************************
 * Author     : xiaohao Z
 * Blog     : http://www.cnblogs.com/shu-xiaohao/
 * Last modified : 2014-05-15 16:59
 * Filename     : C.cpp
 * Description     : 
 * ************************************************/

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <vector>
#include <set>
#include <map>
#define MP(a, b) make_pair(a, b)
#define PB(a) push_back(a)

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<unsigned int,unsigned int> puu;
typedef pair<int, double> pid;
typedef pair<ll, int> pli;
typedef pair<int, ll> pil;

const int INF = 0x3f3f3f3f;
const double eps = 1E-6;
const int LEN = 210;
int Map[LEN][LEN], mp[LEN][LEN], out[LEN], in[LEN], dp[1<<13][20];
int n, m, vn, N;
int xx[] = {0, 0, 1,-1};
int yy[] = {1,-1, 0, 0};
pii vex[LEN];

bool J(int x, int y){
    if(x == 1 || x == n || y == 1 || y == m) return true;
    return false;
}

bool Ja(int x, int y){
    if(x>0 && x<=n && y>0 && y<=m) return true;
    return false;
}

struct P{
    int x, y, val;
    bool operator<(const P a) const
    {
        return this->val > a.val;
    }
};

P mmp(int a, int b, int c){
    P ret;
    ret.x = a;ret.y = b;ret.val = c;
    return ret;
}

int Bfs(int sx, int sy, int ex, int ey){
    int vis[210][210] = {0};
    priority_queue<P> q;
    q.push(mmp(sx, sy, 0));
    vis[sx][sy] = 1;
    while(!q.empty()){
        P nv = q.top();q.pop();
        int x = nv.x, y = nv.y, val = nv.val;
        if(ex < 0 && ey < 0){
             if(J(x, y)) return val;
        }
        else if(x == ex && y == ey) return val;
        for(int i=0; i<4; i++){
            int tx = x + xx[i];
            int ty = y + yy[i];
            if(Ja(tx, ty) && !vis[tx][ty]){
                vis[tx][ty] = 1;
                q.push(mmp(tx, ty, val + mp[tx][ty]));
            }
        }
    }
    return -1;
}

void init(){
    for(int i=0; i<vn; i++){
        for(int j=0; j<vn; j++){
            Map[i][j] = Bfs(vex[i].first, vex[i].second, vex[j].first, vex[j].second);
        }
    }
    for(int i=0; i<vn; i++){
        int x = vex[i].first, y = vex[i].second;
        out[i] = Bfs(x, y, -1, -1);
        in[i] = out[i] + mp[x][y];
    }
}

int dfs(int x, int lv){
    if(dp[x][lv] != INF) return dp[x][lv];
    int cnt = 0;
    for(int i=0; i<vn; i++){
        if(x & (1 << i)) cnt ++ ;
    }
    if(cnt == 1) return dp[x][lv] = in[lv];
    int ret = INF;
    for(int i=0; i<vn; i++){
        if((x & (1<<i)) && i != lv){
            int &val = Map[i][lv];
            ret = min(ret, dfs(x^(1<<lv), i) + val);
        }
    }
    return dp[x][lv] = ret;
}

int main()
{
//    freopen("in.txt", "r", stdin);

    int T, a, b;
    scanf("%d", &T);
    while(T--){
        scanf("%d%d", &n, &m);
        memset(Map, 0x3f, sizeof Map);
        memset(mp, 0, sizeof mp);
        memset(dp, 0x3f, sizeof dp);
        for(int i=1; i<=n; i++){
            for(int j=1; j<=m; j++){
                scanf("%d", &mp[i][j]);
                if(mp[i][j] == -1) mp[i][j] = INF;
            }
        }
        scanf("%d", &vn);
        for(int i=0; i<vn; i++){
            scanf("%d%d", &a, &b);
            a++, b++;
            vex[i] = MP(a, b);
        }
        init();
        int ans = INF;
        for(int i=0; i<vn; i++){
            ans = min(ans, dfs((1<<vn)-1, i) + out[i]);
        }
        if(ans != INF) printf("%d
", ans);
        else printf("0
");
    }
    return 0;
}