LeetCode OJ：Majority Element II（主元素II）

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space.

求主元素，这次的是大于sz/3就算是主元素，可以分为两轮查找，第一轮先查找元素数目较多的两个元素（可能不属于主元素），第二次再遍历来查找上面两个元素是否符合条件，代码如下：

 class Solution {
 public:
     vector<int> majorityElement(vector<int>& nums) {
         int m1, m2;
         int count1, count2;
         vector<int> ret;
         int sz = nums.size();
         if(!sz) return ret;
         m1 = nums[];
         m2 = ;
         count1 = ;
         count2 = ;
         for(int i = ; i < sz; ++i){
             if(m1 == nums[i])
                 count1++;
             else if(m2 == nums[i])
                 count2++;
             else if(count1 == ){
                 count1++;
                 m1 = nums[i];
             }else if(count2 == ){
                 count2++;
                 m2 = nums[i];
             }else{
                 count1--;
                 count2--;
             }
         }
         count1 = count2 = ;
         for(int i = ; i < sz; ++i){
             if(nums[i] == m1) ++count1;
             if(nums[i] == m2) ++count2;
         }
         if(count1 > sz/) ret.push_back(m1);
         if(m1 != m2)
             if(count2 > sz/) ret.push_back(m2);
         return ret;
     }
 };