CCF认证题 搜索题

#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
using namespace std;
int n,m,k,d;
short map[1005][1005],dir[4][2]={{1,0},{0,1},{-1,0},{0,-1}};
bool within(int x,int y){
    if(x<=0||x>n||y<=0||y>n)
        return false;
    return true;
}
struct node{
    int x,y,step;
    node(int a=0,int b=0,int c=0){
        x=a;
        y=b;
        step=c;
    }
};
queue<node> q;
long long bfs(){
    node n;
    int t=0;
    long long sum=0;
    while(!q.empty()){
        n=q.front();
        q.pop();
        int i,x,y;
        for(i=0;i<4;i++){
            x=n.x+dir[i][0];
            y=n.y+dir[i][1];
            if(within(x,y)&&!(map[x][y]&1)){
                map[x][y]|=1;
                if(map[x][y]&2){
                    sum+=(map[x][y]>>2)*(n.step+1);
                    t++;
                    if(t==k)
                        return sum;
                }
                q.push(node(x,y,n.step+1));
            }
        }
    }
}
int main(){
    while(scanf("%d %d %d %d",&n,&m,&k,&d)!=EOF){
        int i,j,x,y;
        memset(map,0,sizeof(map));
        for(i=0;i<m;i++){
            scanf("%d %d",&x,&y);
            map[x][y]|=1;
            q.push(node(x,y,0));
        }
        for(i=0;i<k;i++){
            scanf("%d %d %d",&x,&y,&j);
            map[x][y]=(map[x][y]|2)+(j<<2);
        }
        for(i=0;i<d;i++){
            scanf("%d %d",&x,&y);
            map[x][y]|=1;
        }
        printf("%I64d\n",bfs());
    }
    return 0;
}