leetcode 542. 01 Matrix

class Solution {
public:
    vector<vector<int>> updateMatrix(vector<vector<int>>& matrix) {
        int m = matrix.size(),n = matrix[0].size();
        queue<pair<int,int>> q;
        for(int i = 0;i < m;i++){
            for(int j = 0;j < n;j++){
                if(matrix[i][j] == 0)
                    q.push(make_pair(i,j));
                else
                    matrix[i][j] = INT_MAX;
            }
        }
        while(!q.empty()){
            auto coordinate = q.front();
            q.pop();
            int x = coordinate.first,y = coordinate.second;
            for(auto dir : dirs){
                int new_x = x + dir[0];
                int new_y = y + dir[1];
                if(new_x < 0 || new_x >= matrix.size() || new_y < 0 || new_y >= matrix[0].size() || matrix[new_x][new_y] <= matrix[x][y] + 1)
                    continue;
                matrix[new_x][new_y] = matrix[x][y] + 1;
                q.push(make_pair(new_x,new_y));
            }
        }
        return matrix;
    }
private:
    vector<vector<int>> dirs{{-1,0},{1,0},{0,-1},{0,1}};
};