LeetCode:240. Search a 2D Matrix II(二維資料找數)
阿新 • • 發佈:2018-12-29
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; } }
時間複雜度:O(n)
空間複雜度:O(1)
原始碼github地址:https://github.com/zhangyu345293721/leetcode