Search a 2D Matrix II

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 in ascending from left to right.
Integers in each column are sorted in ascending from top to bottom.

For example,

Consider the following matrix:

[
  [1,   4,  7, 11, 15],
  [2,   5,  8, 12, 19],
  [3,   6,  9, 16, 22],
  [10, 13, 14, 17, 24],
  [18, 21, 23, 26, 30]
]

Given target = 5, return true.

Given target = 20, return false.

Solution:

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