LeetCode Majority Element

1.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.

2.解决方案

class Solution {
public:
    int majorityElement(vector<int> &num) {
        if(num.size() == 1){
            return num[0];
        }
        map<int, int> myMap;
        float majorPercent = num.size() / 2.0;
        for(int i = 0; i < num.size(); ++i){
            int key = num[i];
            if(myMap.find(key) == myMap.end()){
                myMap.insert(pair<int,int>(key,1));
            }else{
                int beforeCount = myMap[key];
                ++beforeCount;
                myMap[key] = beforeCount;
                
                if(beforeCount > majorPercent){
                    return key;
                }
            }
            
        }
        return 0;
    }
};

思路:

用map当然是比较直线的解决方案。值作为key，出现的次数作为value。