题目描述

 

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, returntrue.

 

有序二维矩阵找数，先确定范围再二分查找

1 class Solution { 2 public: 3     bool searchMatrix(vector
      
       
         > &matrix, int target) { 4         int m=matrix.size(),n=matrix[0].size(); 5         int i=0; 6         for(i=0;i
        
         =matrix[i][0]&&target<=matrix[i][n-1]) 8                 break; 9         }10         if(i==m) return false;11         int left=0,right=n-1;12         while(left<=right){13             int mid=(left+right)/2;14             if(target==matrix[i][left]||target==matrix[i][right]||target==matrix[i][mid])15                 return true;16             if(target