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 boolean searchMatrix(int[][] matrix, int target) {
 2         // Start typing your Java solution below
 3         // DO NOT write main() function
 4         int M = matrix.length;
 5         if(M == 0){
 6             return false;
 7         }
 8         int N = matrix[0].length;
 9         if(N == 0){
10             return false;
11         }
12         
13         int row = 0, col = N - 1;
14         while(row < M && col >= 0){
15             if(matrix[row][col] == target){
16                 return true;
17             } else if(matrix[row][col] > target){
18                 col--;
19             } else{
20                 row++;
21             }
22         }
23         return false;
24     }

 

posted @ 2013-08-31 23:03  feiling  阅读(178)  评论(0)  编辑  收藏  举报