LeetCode 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.

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class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int rows = matrix.size();
        if (rows < 1) {
            return false;
        }
        int cols = matrix[0].size();
        if (cols < 1) {
            return false;
        }
        int i = 0;
        int j = cols - 1;
        while (i < rows && j >= 0) {
            int v = matrix[i][j];
            if (v > target) {
                j--;
            } else if (v < target) {
                i++;
            } else {
                return true;
            }
        }
        return false;
    }
};