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73. Set Matrix Zeroes| leetcode solution

 73Set Matrix Zeroes

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's.

You must do it in place.

 

Example 1:

Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]
Output: [[1,0,1],[0,0,0],[1,0,1]]

Example 2:

Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]
Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]

 

Constraints:

  • m == matrix.length
  • n == matrix[0].length
  • 1 <= m, n <= 200
  • -231 <= matrix[i][j] <= 231 - 1

 

Follow up:

  • A straightforward solution using O(mn) space is probably a bad idea.
  • A simple improvement uses O(m + n) space, but still not the best solution.
  • Could you devise a constant space solution?

solution:

class Solution {
public:
    void setZeroes(vector<vector<int>>& matrix) {
         
        int rows = matrix.size();
        int columns = matrix[0].size();
        vector<bool>rows1(columns , 0);
        vector<bool>column1(rows , 0);
        queue<pair<int, int>>q;
        for(int i = 0 ; i < rows ; i++)
        {
            for(int j =0 ; j < columns ; j++)
            {   
                if(matrix[i][j] == 0)
                q.push({i , j});
            }

        }
        while(!q.empty())
        {
            pair<int, int>a = q.front();
                q.pop();
            int i = a.first;
            int j = a.second;
            if(rows1[i] == 0)
            {
            for(int l = 0 ; l < columns; l++)
            {
                matrix[i][l] = 0;

            }
                rows1[i] = 1;
            }
            if(column1[j] == 0)
            {
            for(int m = 0 ; m < rows ; m++)
            {
                matrix[m][j] = 0;

            }
                column1[j] = 1;
            }
            
        

        }
        
    }
};

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