HDU 3309 Roll The Cube(BFS)

Roll The Cube

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <queue>

using namespace std;

int dir[4][2] = {0,1,1,0,0,-1,-1,0};
char map[24][24];
bool vis[24][24][24][24];
int n,m;
struct node {

    int x[2],y[2]; //两个球坐标
    bool ball[2];  //球的状态
    bool hole[2];  //洞的状态
    int step;
    node() {
        ball[0]=ball[1]=hole[0]=hole[1]=false;
        step=0;
    }

    void init() {
        ball[0]=ball[1]=hole[0]=hole[1]=false;
        step=0;
    }

};

node start;
bool check(node &a) {
    for (int i = 0; i < 2; i++) {
        if(a.x[i] < 0 || a.x[i] >= n || a.y[i] < 0 || a.y[i] >= m)
            return false;
    }
    //容易漏掉的判断
    if(a.x[0] == a.x[1]&& a.y[0] == a.y[1] && a.ball[0] == a.ball[1] && a.ball[0] == 0)
        return false;

    if(vis[a.x[0]][a.y[0]][a.x[1]][a.y[1]])
        return false;

    return true;
}

int bfs() {
    memset(vis, 0, sizeof(vis));
    queue<node>q;
    q.push(start);
    vis[start.x[0]][start.y[0]][start.x[1]][start.y[1]] = true;

    node temp;
    while (!q.empty()) {
        start = q.front();
        q.pop();
        for (int i = 0; i < 4; i++) {
            temp = start;
            temp.step++;
            for (int j = 0; j < 2; j++) { //对两个球进行移动
                if(!temp.ball[j]) {//球还没有就位
                    temp.x[j] += dir[i][0];
                    temp.y[j] += dir[i][1];
                    if(map[temp.x[j]][temp.y[j]] == '*') {
                        temp.x[j] -= dir[i][0];
                        temp.y[j] -= dir[i][1];
                    }
                }
            }

            if(check(temp)) {
                vis[temp.x[0]][temp.y[0]][temp.x[1]][temp.y[1]] =  true;
                bool flag = true;

                for (int j = 0; j < 2; j++) { //检查球是否进洞
                    int k = map[temp.x[j]][temp.y[j]]; //强转，利用ascii码表，判断第k个洞的状态
                    //printf("k = %d\n", k);
                    //这里要判断k,重要的地方
                    if((k == 0 || k == 1) && !temp.hole[k]) {//洞里还没球
                        temp.ball[j] = 1;
                        temp.hole[k] = 1;
                    }

                    if(!temp.ball[j])
                        flag = false;
                }

                if(flag)  //都进洞了
                    return temp.step;

                q.push(temp);
            }
        }
    }

    return -1;
}


int main() {

    //freopen("data.in", "r", stdin);
    int t, cnt;
    scanf("%d", &t);
    while (t--) {
        scanf("%d%d", &n, &m);
        getchar();
        cnt = 0;

        bool flag = false;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                scanf("%c", &map[i][j]);
                if(map[i][j] == 'B' && !flag) {
                    start.x[0] = i;
                    start.y[0] = j;
                    flag = true;
                }

                else if(map[i][j] == 'B' && flag) {
                    start.x[1] = i;
                    start.y[1] = j;
                }

                if(map[i][j] == 'H') {
                    map[i][j] = cnt++;
                }
            }

            getchar();
        }

        start.init();
        int ans=bfs();
        if(ans!=-1)
            printf("%d\n",ans);
        else
            printf("Sorry , sir , my poor program fails to get an answer.\n");
    }

    return 0;

}