Write an efficient algorithm that searches for a target value in an m x n integer matrix. The 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 1:
Input: 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]], target = 5
Output: true
Example 2:
Input: 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]], target = 20
Output: false
Constraints:
- m == matrix.length
- n == matrix[i].length
- 1 <= n, m <= 300
- -109 <= matix[i][j] <= 109
- All the integers in each row are sorted in ascending order.
- All the integers in each column are sorted in ascending order.
- -109 <= target <= 109
Solution
class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
int m = matrix.length;
int n = matrix[0].length;
int row = 0;
int col = n - 1;
while (row < m && col >= 0) {
int value = matrix[row][col];
if (value == target) return true;
if (target < value) {
col--;
} else {
row++;
}
}
return false;
}
}