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01matrix_leetcode.cpp
38 lines (38 loc) · 1.19 KB
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01matrix_leetcode.cpp
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class Solution {
public:
vector<vector<int>> updateMatrix(vector<vector<int>>& mat) {
int n=mat.size();
int m=mat[0].size();
vector<vector<int>> dist(n,vector<int>(m,0));
vector<vector<int>> vis(n,vector<int>(m,0));
queue<pair<pair<int,int>,int>>q;
int arr_row[4]={-1,0,1,0};
int arr_col[4]={0,1,0,-1};
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
if(mat[i][j]==0){
dist[i][j]=0;
vis[i][j]=1;
q.push({{i,j},0});//multi spource bfs
}
}
}
int dm=0;
while(!q.empty()){
int r=q.front().first.first;
int c=q.front().first.second;
int d=q.front().second;
q.pop();
dist[r][c]=d;
for(int i=0;i<4;i++){
int nrow=r+arr_row[i];
int ncol=c+arr_col[i];
if(nrow>=0 && nrow<mat.size() && ncol>=0 && ncol<mat[0].size() && vis[nrow][ncol]==0){
vis[nrow][ncol]=1;
q.push({{nrow,ncol},d+1});
}
}
}
return dist;
}
};