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
.
C++实现代码如下:
#include<iostream>
#include<vector>
using namespace std;
class Solution
{
public:
bool searchMatrix(vector<vector<int> > &matrix, int target)
{
if(matrix.empty()||matrix[0].empty())
return false;
int i=0;
int j=matrix[0].size()-1;
int temp;
while(i<(int)matrix.size()&&j>=0)
{
temp=matrix[i][j];
if(target==temp)
return true;
else if(target<temp)
j--;
else if(target>temp)
i++;
}
return false;
}
};
int main()
{
Solution s;
vector<vector<int> > vec=
{
{-10,-9},
{-7,-6},
{-5,-4},
{-3,-2}
};
cout<<s.searchMatrix(vec,-6)<<endl;
}
class Solution {
public:
bool searchMatrix(vector<vector<int> > &matrix, int target) {
if(matrix.empty()||matrix[0].empty())
return false;
size_t i=0;
size_t j=matrix[0].size()-1;
int temp;
while(i<matrix.size()&&j>=0)
{
temp=matrix[i][j];
if(target==temp)
return true;
if(target<temp)
{
j--;
continue;
}
if(target>temp)
{
i++;
continue;
}
}
if(i>=matrix.size()||j<0)
return false;
return true;
}
};