Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
For example,
Consider the following matrix:
[ [1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 50] ]
Given target = 3, return true.
class Solution {
public:
bool searchMatrix(vector<vector<int>>& matrix, int target) {
int M=matrix.size();
int N=matrix[0].size();
int top=0;
int bottom=M-1;
int mid1=0;
if(matrix[0][0]==target)
return true;
while(top<=bottom)
{
mid1=top+(bottom-top)/2;
if(matrix[mid1][0]==target)
return true;
else if(matrix[mid1][0]<target)
top=mid1+1;
else
bottom=mid1-1;
}
if(matrix[mid1][0]>target)
{
if(mid1>0)
mid1--;
else
return false;
}
int left=0;
int right=N-1;
while(left<=right)
{
int mid2=left+(right-left)/2;
if(matrix[mid1][mid2]==target)
return true;
else if(matrix[mid1][mid2]<target)
left=mid2+1;
else
right=mid2-1;
}
return false;
}
};leetcode No74. Search a 2D Matrix
原文：http://blog.csdn.net/u011391629/article/details/52122470