Tags: "leetcode", "matrix", "divide-and-conquer", access_time 1-min read

# 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.

### 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

``````class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
return false;
}

int row = matrix.length - 1;
int col = 0;

while (row >= 0 && col < matrix[0].length) {
if (matrix[row][col] > target) {
row--;
} else if (matrix[row][col] < target) {
col++;
} else {
// found it
return true;
}
// continue searching
}

return false;
}
}
``````