Search a 2d Matrix II
Created: April 2, 2019 by [lek-tin]
Last updated: September 19, 2019
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;
}
}