Problem: Search a 2D Matrix II

Question

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.

Solutions

TODO

Code

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

Performance