class Solution { public: int maxDistance(vector<vector<int>>& grid) { vector<pair<int,int>>wa,la; int n=size(grid); for(int i=0;i<n;i++)for(int j=0;j<n;j++) if(grid[i][j])la.emplace_back(i,j);else wa.emplace_back(i,j); if(wa.empty()||la.empty())return -1; int r=0; for(auto&[i,j]:wa) { int m=1e9; for(auto&[x,y]:la)m=min(m,abs(i-x)+abs(j-y)); r=max(r,m); } return r; } };

O(n^4)이 뚫리는 건 절대 제 잘못이 아님 ㅋ