leetcode_169题——Majority Element（采用的map来做的）

Majority Element

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Question  Solution 

 

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.

You may assume that the array is non-empty and the majority element always exist in the array.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

 

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  Divide and Conquer Array Bit Manipulation

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      这道题的要求是找到行向量中出现次数最多的数字，而在题目中好像希望可以用分治法来做，但是我采用的map来做的，因为这个记录起来很快，map查找的时间复杂度很小，<int,int> first中储存值。second储存值出现的次数

#include<iostream>

#include <vector>

#include <map>

#include <utility>

using namespace std;



int majorityElement(vector<int>& nums) {

	map<int,int> temp;

	int len=nums.size();

	int result;

	if(len==1)

	{

		result=nums[0];

		return result;

	}

	for(int i=0;i<len;i++)

	{

		if(temp.count(nums[i])==0)

		{

			temp.insert(make_pair(nums[i],1));

		}

		else

		{

			temp[nums[i]]++;

		}

	}

	pair<int,int>max_num(temp.begin()->first,temp.begin()->second);

	for(map<int,int>::iterator i=temp.begin();i!=temp.end();i++)

	{

		if(i->second>max_num.second)

		{

			max_num.first=i->first;

			max_num.second=i->second;

		}

	}

	result=max_num.first;

	return result;

}

int main()

{

	vector<int> vec;

	vec.push_back(2),vec.push_back(2);

	cout<<majorityElement(vec)<<endl;

}