POJ 2312 Battle City

bfs+优先队列

代码

//bfs
//#include<bits/stdc++.h>
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
#define CL(a,b) memset(a,b,sizeof(a))
const int maxm=305;
const int maxn=305;
char mp[maxm][maxn];
int vis[maxm][maxn];//记录是否处理过
struct node{
    int x,y;
    int step;
    node(int x_,int y_,int s_):x(x_),y(y_),step(s_){}
};
 bool operator < (node a,node b){
        return a.step>b.step;
    }
int mv[4][2]={{-1,0},{1,0},{0,-1},{0,1}};
//优先队列

int m,n;
int bfs(node begin,int endx,int endy){
    priority_queue<node> que;
    vis[begin.x][begin.y]=1;
    que.push(begin);
    while(!que.empty()){
        node tmp=que.top();
        que.pop();
        //printf("db %d %d step %d
",tmp.x,tmp.y,tmp.step);
        if(tmp.x==endx&&tmp.y==endy) return tmp.step;
        int tmpx,tmpy,tmps;
        for(int i=0;i<4;i++){
            tmpx=tmp.x+mv[i][0];
            tmpy=tmp.y+mv[i][1];
            if(tmpx<0||tmpx>=m||tmpy<0||tmpy>=n||vis[tmpx][tmpy]||mp[tmpx][tmpy]=='S'||mp[tmpx][tmpy]=='R') continue;//依旧可能出现相同坐标都在队列中
            else if(mp[tmpx][tmpy]=='B') tmps=tmp.step+2;
            else tmps=tmp.step+1;
            node t=node(tmpx,tmpy,tmps);
            vis[tmpx][tmpy]=1;
            que.push(t);
            //else if(mp[tmpx][tmpy]=='B'){node t=node(tmpx,tmpy,tmp.step+2);vis[tmpx][tmpy]=1;que.push(t);}
            //else if(mp[tmpx][tmpy]=='E'||mp[tmpx][tmpy]=='T'){node t=node(tmpx,tmpy,tmp.step+1);vis[tmpx][tmpy]=1;que.push(t);}

        }
    }
    return -1;//no find
}
node beg=node(0,0,0);
int endx,endy;
int main(){
    while(scanf("%d %d",&m,&n)&&m!=0){
        //CL(mp,0);
        CL(vis,0);
        /*
        while(!que.empty()){
            que.pop();
        }
        */
        for(int i=0;i<m;i++){
            scanf("%s",mp[i]);
            for(int j=0;j<n;j++){
                if(mp[i][j]=='Y'){
                    beg.x=i,beg.y=j,beg.step=0;
                }
                if(mp[i][j]=='T'){
                    endx=i,endy=j;
                }
            }
        }
        int ans=bfs(beg,endx,endy);
        printf("%d
",ans);
    }
    return 0;
}

发现

对运算符的重载放在结构体外面更快，16ms-->0ms