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.

Hint:

  1. How many majority elements could it possibly have?
  2. Do you have a better hint? Suggest it!
     1 class Solution {
     2 public:
     3     vector<int> majorityElement(vector<int>& nums) {
     4         int i;
     5         int count1,count2;
     6         int num1,num2;
     7         int n=nums.size();
     8         vector<int> res;
     9         count1=0;
    10         count2=0;
    11         for(i=0;i<n;i++){
    12             if(count1==0 || num1==nums[i]){
    13                 num1=nums[i];
    14                 count1++;
    15             }
    16             else if(count2==0 || num2==nums[i]){
    17                     num2=nums[i];
    18                     count2++;
    19                 }
    20             else
    21             {
    22                 count1--;
    23                 count2--;
    24             }
    25         }
    26         count1=0;
    27         count2=0;
    28         for(i=0;i<n;i++)
    29         {
    30             if(num1==nums[i])
    31               count1++;
    32             else if(num2==nums[i])
    33               count2++;
    34             
    35         }
    36         if(count1>n/3)
    37           res.push_back(num1);
    38         if(count2>n/3)
    39           res.push_back(num2);
    40           return res;
    41     }
    42 };

     

posted @ 2015-07-23 12:29  鸭子船长  阅读(196)  评论(0编辑  收藏  举报