LightOJ 1238 Power Puff Girls（BFS）

题解;

对a,b,c三个点各求一次bfs然后取最大值即可

代码

#include <cstdio>#include <queue>#include <cstring>#include <iostream>#include <cstdlib>#include <algorithm>#include <vector>#include <map>#include <string>#include <set>#include <ctime>#include <cmath>#include <cctype>using namespace std;#define maxn 100000#define LL long longint cas=1,T;int n,m;char mapp[25][25];int visit[25][25];int dx[] = {0,0,1,-1};int dy[] = {1,-1,0,0};struct Node{    int x,y;   int step;};bool check(int x,int y){    if (x<0 || y<0 || x>=n || y>=m)        return true;    if (visit[x][y] || mapp[x][y]=='#' || mapp[x][y]=='m' )        return true;    return false;}int bfs(Node s){   visit[s.x][s.y]=1;   queue<Node> q;   q.push(s);   while (!q.empty())   {       Node t = q.front();       q.pop();       if (mapp[t.x][t.y]=='h')           return t.step;       for (int i = 0;i<4;i++)       {           Node temp;           temp.x = t.x+dx[i];           temp.y = t.y+dy[i];           if (check(temp.x,temp.y))               continue;           visit[temp.x][temp.y]=1;           temp.step = t.step+1;           q.push(temp);       }   }   //memset(visit,0,sizeof(visit));}int main(){    scanf("%d",&T);    while (T--)    {        printf("Case %d: ",cas++);        Node a,b,c;        scanf("%d%d",&n,&m);        for (int i = 0;i<n;i++)            scanf("%s",&mapp[i]);        int atime,btime,ctime;        for (int i = 0;i<n;i++)            for (int j = 0;j<m;j++)            {               if (mapp[i][j]=='a')               {                   a.x=i;                   a.y=j;                   a.step=0;                   atime = bfs(a);                   memset(visit,0,sizeof(visit));               }               if (mapp[i][j]=='b')               {                   b.x=i;                   b.y=j;                   b.step=0;                   btime = bfs(b);                   memset(visit,0,sizeof(visit));               }               if (mapp[i][j]=='c')               {                   c.x=i;                   c.y=j;                   c.step=0;                   ctime = bfs(c);                   memset(visit,0,sizeof(visit));               }            }        int mins =0;        mins = max(atime,max(btime,ctime));        printf("%d\n",mins);        memset(mapp,0,sizeof(mapp));        memset(visit,0,sizeof(visit));    }    //freopen("in","r",stdin);    //scanf("%d",&T);    //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);    return 0;}