标签：c++   leetcode   算法   

题目：

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

思路：先从行找到合适的位置，使用二分查找，再在这一行查找目标值，也是二分查找，时间复杂度为O(lgm + lgn)

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

/*
在一个二维数组中查找一个元素 只不过这个数组是有特殊排序的
使用二分查找 
*/ 

bool Search2DMatrix(vector<vector<int> >& vec,int key)
{
	int pos;
	int low,high,mid;
	low = 0;
	high = vec.size()-1;
	while(low<=high)
	{
		mid = low+(high-low)/2;
		if(vec[mid][0] == key)
			return true;
		else if(vec[mid][0] > key)
		 	high= mid-1;
		else
			low = mid+1;
	}
	pos = mid;
	
	low = 0;
	high = vec[0].size()-1;
	while(low<=high)
	{
		mid = low+(high-low)/2;
		if(vec[pos][mid] == key)
			return true;
		else if(vec[pos][mid]>key)
			high = mid-1;
		else
			low = mid+1; 
	}
	return false;
}

int main()
{
	vector<vector<int> > vec;
	int array[]={1,3,5,7};
	int array1[]={10,11,16,20};
	int array2[]={23,30,34,50};
	vector<int> vec1(array,array+sizeof(array)/sizeof(int));
	vec.push_back(vec1);
	vector<int> vec2(array1,array1+sizeof(array1)/sizeof(int));
	vec.push_back(vec2);
	
	vector<int> vec3(array2,array2+sizeof(array2)/sizeof(int));
	vec.push_back(vec3);
	
	cout<<Search2DMatrix(vec,300);
	return 0;
}

Search a 2D Matrix--LeetCode

标签：c++   leetcode   算法   

原文地址：http://blog.csdn.net/yusiguyuan/article/details/44854959