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.

解题思路：摩尔投票法。这种投票法先将第一个数字假设为众数，然后把计数器设为1，比较下一个数和此数是否相等，若相等则计数器加一，反之减一。

实现代码：

// Runtime: 20 msclass Solution {public:    int majorityElement(vector
    
     & nums) {        int n = nums[0];        int c = 1;        for (int i = 0; i < nums.size(); i++)        {            n == nums[i] ? c++ : c--;            if (c == 0)            {                n = nums[i];                c = 1;            }        }        return n;    }};