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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.

 

第一种方法:

存到hashmap中,然后找出现次数多于一半的。

 1 public class Solution { 2     public int majorityElement(int[] num) { 3         HashMap<Integer, Integer> map = new HashMap<Integer, Integer>(); 4         for(int n : num){ 5             if(map.containsKey(n)) map.put(n, map.get(n) + 1); 6             else map.put(n, 1); 7         } 8         for(int i : map.keySet()){ 9             if(map.get(i) > num.length / 2) return i;10         }11         return -1;12     }13 }

 

Majority Element