Fzu 2186 小明的迷宮（狀態壓縮dp + bfs）

注意：

有兩種情況起點為負數，財寶之間不能聯通，這兩種情況要輸出-1；存在一個財寶且財寶在原點，這種情況要輸出0。

AC代碼

#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 105;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = { 0,-1, 0, 1};

struct Point {
    int x, y;
    Point() {}
    Point(int _x, int _y) {
        x = _x, y = _y;
    }
}poi[20];

struct Node {
    int x, y, dist;
    Node() {}
    Node(int _x, int _y, int _dist) {
        x = _x; y = _y; dist = _dist;
    }
};

int grid[N][N], dist[20][20], dp[(1<<12)][20];
int n, m, tot;
bool vis[N][N];

int bfs(int star, int end) {
    memset(vis, false, sizeof(vis));
    queue que;
    que.push(Node(poi[star].x, poi[star].y, 0));
    int step, x, y;
    while(!que.empty()) {
        Node front = que.front();
        que.pop();
        if(front.x == poi[end].x && front.y == poi[end].y)
            return front.dist;
        for(int i = 0; i < 4; i++) {
            x = front.x + dx[i];
            y = front.y + dy[i];
            if(x < 1 || x > n || y < 1 || y > m || grid[x][y] < 0) continue;
            if(!vis[x][y]) {
                vis[x][y] = true;
                step = front.dist + 1;
                que.push(Node(x, y, step));
            }
        }
    }
    return -1;
}

bool getDist() {
    memset(dist, 0, sizeof(dist));
    for(int i = 0; i <= tot; i++) {
        for(int j = 0; j < i; j++) {
            dist[i][j] = dist[j][i] = bfs(i, j);
            if(dist[i][j] == -1) return false;
        }
    }
    return true;
}

int tsp() {
    memset(dp,INF,sizeof(dp));
    dp[1][0] = 0;
    int end = (1<<(tot+1)) - 1;
    for (int st=0; st <=end; st++)
        for(int i=0; i <= tot; i++)
            for(int j=0;j <= tot; j++) {
                if (i == j) continue;
                if ((1 << i) & st == 0 || (1 << j) & st == 1) continue;
                if (dp[st][i] == INF) continue;
                dp[st|(1< 0)
                    poi[++tot] = Point(i, j);
            }
        }
        if(tot == 0) {
            puts("0");
            continue;
        }
        poi[0] = Point(1, 1);
        if(grid[1][1] < 0 || !getDist()) {
            puts("-1");
            continue;
        }
        printf("%d\n", tsp());
    }
    return 0;
}