LeetCode Search a 2D Matrix

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 from left to right.
  • The first integer of each row is greater than the last integer of the previous row.

 

For example,

Consider the following matrix:

[
  [1,   3,  5,  7],
  [10, 11, 16, 20],
  [23, 30, 34, 50]
]

Given target = 3, return true.

 

 1 public class Solution {
 2     public boolean searchMatrix(int[][] matrix, int target) {
 3             int line=0;
 4         if (matrix.length<1) {
 5             return false;
 6         }
 7         if (target<matrix[0][0]) {
 8             return false;
 9         }
10         for (int i = 1; i < matrix.length; i++) {
11             if (matrix[i][0]>target) {
12                 line=i-1;
13                 break;
14             }
15             if (matrix[i][0]==target) {
16                 return true;
17             }
18         if (matrix[i][matrix[i].length-1]>=target) {
19             line=i;
20         }            
21         }
22 
23         for (int is : matrix[line]) {
24             if (is==target) {
25                 return true;
26             }
27         }
28         return false;
29     }
30 }

 

posted @ 2014-10-16 11:28  birdhack  阅读(108)  评论(0)  编辑  收藏  举报