南陽理工OJ_題目82 迷宮尋寶（一）

//bfs 
#include <iostream>
#include <cstring>
#include <queue>

using namespace std;

bool bfs(int x, int y);

struct data
{
    int x;
    int y;
};

int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};

int m;
int n;
int s_x;	//S的座標 
int s_y;
int g_x;	//G的座標 
int g_y;
int a, b, c, d, e;	//a~e的個數 
int aa, bb, cc, dd, ee;	//已經找到的a~e的個數 
char g[25][25];
int vis[25][25];

int main()
{
    while(cin >> m >> n, m + n)
    {
        a = b = c = d = e = 0;
        aa = bb = cc = dd = ee = 0;
        memset(g, 'X', sizeof(g));
        for(int i = 1; i <= m; i++)
            for(int j = 1; j <= n; j++)
            {
                cin >> g[i][j];
                switch(g[i][j])
                {
                    case 'a': a++; break;
                    case 'b': b++; break;
                    case 'c': c++; break;
                    case 'd': d++; break;
                    case 'e': e++; break;
                    case 'S': s_x = i; s_y = j; break;
                    case 'G': g_x = i; g_y = j; break;
                }
            }
        int flag = 0;
        for(int i = 0; i <= 5; i++)
        {
            memset(vis, 0, sizeof(vis));
            if(bfs(s_x, s_y))
            {
                flag = 1;
                break;
            }
        }
        if(flag == 1)
            cout << "YES\n";
        else
            cout << "NO\n";
    }
}

bool bfs(int x, int y)
{
    queue<data> q;
    data t1, t2;
    t1.x = x;
    t1.y = y;
    q.push(t1);
    vis[x][y] = 1;
    while(!q.empty())
    {
        t1 = q.front();
        q.pop();
        for(int i = 0; i < 4; i++)
        {
            int xx = t1.x + dx[i];
            int yy = t1.y + dy[i];
            if(g[xx][yy] == 'G')
                return true;
            if(g[xx][yy] == 'X' || vis[xx][yy] == 1)
                continue;
            if(g[xx][yy] >= 'A' && g[xx][yy] <= 'E')
            {
                switch(g[xx][yy])
                {
                    case 'A': if(a == aa) g[xx][yy] = '.'; break;
                    case 'B': if(b == bb) g[xx][yy] = '.'; break;
                    case 'C': if(c == cc) g[xx][yy] = '.'; break;
                    case 'D': if(d == dd) g[xx][yy] = '.'; break;
                    case 'E': if(e == ee) g[xx][yy] = '.'; break;
                }
            }
            if(g[xx][yy] == '.' || (g[xx][yy] >= 'a' && g[xx][yy] <= 'e'))
            {
                t2.x = xx;
                t2.y = yy;
                q.push(t2);
                vis[xx][yy] = 1;
                switch(g[xx][yy])
                {
                    case 'a': aa++; break;
                    case 'b': bb++; break;
                    case 'c': cc++; break;
                    case 'd': dd++; break;
                    case 'e': ee++; break;
                }
                g[xx][yy] = '.';
            }
        }
    }
    return false;
}