240. 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.

For 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.

代碼如下：

 1 public class Solution {
 2     public boolean searchMatrix(int[][] matrix, int target) {
 3         List<Integer> list=new ArrayList<>();
 4         for(int i=0;i<matrix.length;i++)
 5         {
 6             for(int j=0;j<matrix[i].length;j++){
 7                 list.add(matrix[i][j]);
 8             }
 9         }
10         if(list.contains(target))
11         return true;
12         
13         return false;
14     }
15 }