（2016弱小联盟十一专场10.3） Help the Princess! BFS

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题目连接：
https://acm.bnu.edu.cn/v3/statments/jag2016.pdf

分析：

直接判断‘%’到‘@’和最近的‘$’的距离，如果 ‘%’到‘@’小于%’到最近的‘$’的距离则输出YES否则输出NO

AC代码：

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <cmath>using namespace std;const int maxn = 210;char mmap[maxn][maxn];int h,w;int ansp,anss;int dir[2][4] = {0,0,1,-1,1,-1,0,0};bool vis[maxn][maxn];struct node{    int x,y,step;};void bfs(int x,int y){    memset(vis,false,sizeof(vis));    queue<node> q;    node now,ne;    now.x = x; now.y = y; now.step = 0;    q.push(now);    vis[x][y] = true;    while(!q.empty())    {        now = q.front();        q.pop();        for(int i=0;i<4;i++)        {            ne.x = now.x + dir[0][i];            ne.y = now.y + dir[1][i];            if(!vis[ne.x][ne.y] && ne.x >= 1 && ne.x <= h && ne.y >= 1 && ne.y <= w && mmap[ne.x][ne.y]!='#')            {                ne.step = now.step + 1;                vis[ne.x][ne.y] = true;                if(mmap[ne.x][ne.y] == '@')                    ansp = min(ne.step,ansp);                else if(mmap[ne.x][ne.y] == '$')                    anss = min(ne.step,anss);                q.push(ne);            }        }        if(ansp < 9999999 && anss < 9999999) break;    }}int main(){    while(scanf("%d%d",&h,&w)!=EOF)    {        int x,y;        ansp = anss = 9999999;        getchar();        for(int i=1;i<=h;i++)        {            for(int j=1;j<=w;j++)            {                scanf("%c",&mmap[i][j]);                if(mmap[i][j] == '%')                {                    x = i; y = j;                }            }            getchar();        }        bfs(x,y);        if(ansp < anss) printf("Yes\n");        else printf("No\n");    }    return 0;}

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