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.
Analysis: 每找出两个不同的element就成对删除，最后可能剩两个元素或一个元素，必定都是所求
Solution 1: 使用vector.erase
可扩展到⌊ n/k ⌋的情况，每k个不同的element进行成对删除。
【LeetCode】169 - Majority Element
原文：http://www.cnblogs.com/irun/p/4722615.html