LeetCode 169: Majority Element

題目鏈接：

https://leetcode.com/problems/majority-element/description/

描述

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.

算法思想：

可以使用STL中的map來解決這個問題比較方便，如果使用數組來解決對於負數和最大數特別大時將無能爲力。使用map的first來存儲nums中的數據，second來存儲其個數。

源代碼

/*
Author:楊林峯
Date:2017.12.30
LeetCode(169):主元
*/
class Solution {
public:
    int majorityElement(vector<int>& nums) {
        map<int,int> m;
        int sz = nums.size();
        for(int i = 0;i < sz;i++)
        {
            m[nums[i]]++;
        }
        map<int,int>::iterator it;
        for(map<int,int>::iterator it = m.begin();it != m.end();it++)
        {
            if(!(sz%2) && it->second >= sz/2 || it->second > sz/2)
            {
                return it->first;
            }

        }
        return 0;
    }
};