Set Matrix Zeroes (LeetCode Array)

Question: Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.

Idea: First check whether the first row and the first column has zeros. Then use the first row and the first column as the buffer. If the matrix[i][j]==0 (i>=1, j>=1), set matrix[i][0] and matrix[0][j]=0. Then set each row i to zeros if matrix[i][0]==0, set each column j to zeros if matrix[0][j]==0. At last, set the first row and the first column to zeros according to the results of first step.

Time: O(n^2) Space: O(1)

Code:

 public class Solution {  
   public void setZeroes(int[][] matrix) {  
     boolean rowHasZero=false;  
     boolean columnHasZero=false;  
     for(int i=0;i<matrix.length;i++)  
     {  
       if(matrix[i][0]==0)  
       {  
         columnHasZero=true;  
         break;  
       }  
     }  
     for(int j=0;j<matrix[0].length;j++)  
     {  
       if(matrix[0][j]==0)  
       {  
         rowHasZero=true;  
         break;  
       }  
     }  
     for(int i=1;i<matrix.length;i++)  
     {  
       for(int j=1;j<matrix[0].length;j++)  
       {  
         if(matrix[i][j]==0)  
         {  
           matrix[i][0]=0;  
           matrix[0][j]=0;  
         }  
       }  
     }  
     for(int i=1;i<matrix.length;i++)  
     {  
       for(int j=1;j<matrix[0].length;j++)  
       {  
         if(matrix[i][0]==0||matrix[0][j]==0)  
           matrix[i][j]=0;  
       }  
     }        
     if(rowHasZero)  
     {  
       for(int j=0;j<matrix[0].length;j++)  
         matrix[0][j]=0;  
     }  
     if(columnHasZero)  
     {  
       for(int i=0;i<matrix.length;i++)  
         matrix[i][0]=0;  
     }  
   }  
 }