Emptying the Baltic（类似最短路？）

来源：互联网发布：美萍软件怎么样编辑：程序博客网时间：2024/06/16 04:57

题目：https://odzkskevi.qnssl.com/da9adfb686ef541a14cec9856721130a?v=1507986802

从排水口（sx，sy）开始，压入优先队列，每次去队头元素，与八个方向上的流量比较，知道队列为空

#include<cstdio>#include<cmath>#include<cstring>#include<algorithm>#include<iostream>#include<queue>using namespace std;struct node{int x,y,dep;node(int x,int y,int dep):x(x),y(y),dep(dep){}bool operator<(const node &a)const{return dep>a.dep;}};int n,m;long long sum;int sx,sy;int vis[550][550];int a[550][550];int d[8][2]={0,1,0,-1,1,0,-1,0,1,1,1,-1,-1,1,-1,-1};int check(int x,int y){return x>=1&&x<=n&&y>=1&&y<=m&&!vis[x][y]&&a[x][y]<0;}void bfs(){priority_queue<node>q;memset(vis,0,sizeof(vis));q.push(node(sx,sy,a[sx][sy]));sum=-a[sx][sy];vis[sx][sy]=1;while(!q.empty()){node now=q.top();q.pop();for(int i=0;i<8;i++){int x=now.x+d[i][0];int y=now.y+d[i][1];if(check(x,y)){vis[x][y]=1;sum-=max(now.dep,a[x][y]);q.push(node(x,y,max(now.dep,a[x][y])));}}}}int main(){scanf("%d%d",&n,&m);int i,j;for(i=1;i<=n;i++){for(j=1;j<=m;j++){scanf("%d",&a[i][j]);}}scanf("%d%d",&sx,&sy);bfs();printf("%lld\n",sum);return 0;}

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