73. Set Matrix Zeroes¶

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73. Set Matrix Zeroes

Medium

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(int[][] matrix) {
        int n=matrix.length;
        int m=matrix[0].length;
        ArrayList<Integer> row=new ArrayList<>();
        ArrayList<Integer> col=new ArrayList<>();
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(matrix[i][j]==0){
                    row.add(i);
                    col.add(j);
                }
            }
        }
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(row.contains(i)||col.contains(j)){
                    matrix[i][j]=0;
                }
            }
        }
    }
}

Complexity Analysis¶

• Time Complexity: O(?)
• Space Complexity: O(?)

Approach¶

Detailed explanation of the approach will be added here