Majority Element 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.

 

Analyse: map. 

Runtime: 40ms.

 1 class Solution {
 2 public:
 3     vector<int> majorityElement(vector<int>& nums) {
 4         int n = nums.size();
 5         map<int, int> m;
 6         vector<int> result;
 7         
 8         for(int i = 0; i < n; i++){
 9             if(m.find(nums[i]) != m.end())
10                 m[nums[i]]++;
11             else
12                 m[nums[i]] = 1;
13         }
14         
15         for(map<int, int>::iterator ite = m.begin();  ite != m.end(); ite++){
16             if(ite->second > n / 3)
17                 result.push_back(ite->first);
18         }
19         return result;
20     }
21 };

 

posted @ 2015-09-12 02:45  amazingzoe  阅读(130)  评论(0)    收藏  举报