#include<bits/stdc++.h> using namespace std; int n,m,ans=0; char c[505][505]; int fx[4]={-1,0,1,0}; int fy[4]={0,1,0,-1}; struct node{ int x,y; }; queue<node> q; int main(){ cin>>n>>m; for(int i=1;i<=n;i++) for(int j=1;j<=m;j++){ cin>>c[i][j]; } for(int i=1;i<=n;i++) for(int j=1;j<=m;j++){ if((i==1||i==n||j==1||j==m)&&c[i][j]=='0'){//在区域周围且能淹没 q.push({i,j}); c[i][j]='*';//淹没后默认为墙 } } while(!q.empty()){//直至全部淹没停止 int x=q.front().x; int y=q.front().y; for(int i=0;i<=3;i++){ int tx=x+fx[i],ty=y+fy[i]; if(tx>=1&&tx<=n&&ty>=1&&ty<=m&&c[tx][ty]=='0'){ q.push({tx,ty}); c[tx][ty]='*';//淹没后默认为墙 } } q.pop(); } for(int i=1;i<=n;i++){ for(int j=1;j<=m;j++){ if(c[i][j]=='0') ans++; } } cout<<ans; return 0; } /************************************************************** Problem: 1913 User: fuhongyi Language: C++ Result: Accepted Time:29 ms Memory:2328 kb ****************************************************************/