Boyer-Moore Voting Algorithm 这个算法好巧妙啊！简直妙不可言！
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.
Example 1:
Input: [3,2,3] Output: 3
Example 2:
Input: [2,2,1,1,1,2,2] Output: 2
link:{sourcedir}/_0169_MajorityElement.java[role=include]