74 Search a 2D Matrix

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

Integers in each row are sorted from left to right.
The first integer of each row is greater than the last integer of the previous row.
Example 1:

Input:
matrix = [
  [1,   3,  5,  7],
  [10, 11, 16, 20],
  [23, 30, 34, 50]
]
target = 3
Output: true

public boolean searchMatrix(int[][] matrix, int target) {
        
        if(matrix.length==0)return false;
        
      int i = 0 , j = matrix[0].length-1;
        
      while(i<matrix.length  && j>=0){
          
         if(matrix[i][j]>target){ //7>4
             j--;
         }else if (matrix[i][j]<target){
             i++;
         }else{
             return true;
         }
          
      }
        
        
        return false;
    }