169- Majority Element

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.

class Solution {
public:
    int majorityElement(vector<int>& nums) {
        map<int, int> num_count;
        for(vector<int>::size_type i = 0; i < nums.size(); i++) {
        	++num_count[nums[i]];
        }
		map<int, int>::iterator it = num_count.begin();
		for(; it != num_count.end(); it++) {
			if( it->second > nums.size() / 2) {
				return it->first;
			}			
		}
		return 0;
    }
};

这篇博客介绍的很好，思路很多：http://www.cnblogs.com/EdwardLiu/p/4179345.html