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
.
方法1:
class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
int row = matrix.length;
if (row == 0) return false;
int col = matrix[0].length;
int i = 0;
int j = col - 1;
while (i < row && j >= 0) {
if (matrix[i][j] == target)
return true;
else if (matrix[i][j] > target)
j--;
else
i++;
}
return false;
}
}
时间复杂度:O(n)
空间复杂度:O(1)
源码github地址:https://github.com/zhangyu345293721/leetcode