https://www.luogu.org/problem/P1162
思路：将图从1-n存起来，外面一圈用0填充,然后从(0,0)开始搜
// luogu-judger-enable-o2 #include <cstdio> #include <iostream> #include <algorithm> #include <cmath> #include <queue> #include <vector> #include <cstring> #include <map> #define mem(a) memset(a,0,sizeof(a)) using namespace std; typedef long long lll; const int maxn = 200005; const lll INF = 0x3f3f3f3f3f; int dir[8][2]= {0,1,0,-1,1,0,-1,0,-1,-1,1,-1,-1,1,1,1}; int dir2[4][2]= {0,1,0,-1,1,0,-1,0}; bool flag; int a[35][35],b[35][35],n; struct node{ int x,y; node(){}; node(int xx,int yy):x(xx),y(yy){}; }; void bfs(int x,int y) { queue<node>q; q.push(node(0,0));//(0,0)一定是0 while(!q.empty()){ int fx = q.front().x,fy = q.front().y; q.pop(); b[fx][fy] = 3;//将圈外的0标记为3 for(int i=0;i<4;i++) { int ex = fx + dir2[i][0],ey = fy + dir2[i][1]; if(ex < 0 || ex > n+1 || ey < 0 || ey > n + 1 || b[ex][ey] == 1 || b[ex][ey] == 3) continue; q.push(node(ex,ey)); } } } int main() { cin >> n; for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++){ cin >> a[i][j]; if(a[i][j] == 0) b[i][j] = 2; else b[i][j] = 1; } bfs(0,0); for(int i = 1; i <= n; i++){ for(int j =1; j <= n; j++){ if(b[i][j] == 3 ) cout << "0"; else cout << b[i][j]; if(j < n) cout << " "; else cout << endl; } } return 0; }