【LeetCode OJ】Majority Element

题目：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.

 1 int majorityElement(vector<int> &num)

 2 {

 3     map<int, int> m;

 4     int n = num.size() / 2;

 5     for (vector<int>::iterator it = num.begin(); it != num.end(); it++)

 6     {

 7         auto ret = m.insert(make_pair(*it, 1));  //对于不包含重复关键字的容器map,insert操作返回一个pair

 8         if (!ret.second)        //pair的firs成员是一个迭代器，指向具有给定关键字的元素，

 9             ++ret.first->second;//second成员是一个bool值，指出元素的插入成功还是已经存在于容器中，如果已存在，则返回bool为false

10 

11     }

12     for (map<int, int>::iterator it = m.begin(); it != m.end(); it++)

13     {

14         if (it->second > n)

15             return it->first;

16     }

17 }