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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.
这道题我没有看提示，直接用hash表，遍历数组，将出现的次数保存到hash表中，最后遍历hash表，找出满足要求的元素。时间复杂度为O(n)
1 import java.util.Hashtable; 2 import java.util.Iterator; 3 4 public class Solution { 5 public int majorityElement(int[] num) { 6 Hashtable<Integer, Integer> hashtable = new Hashtable<Integer, Integer>(); 7 int result = 0; 8 9 for(int i = 0; i < num.length; i++){ 10 Integer times = hashtable.get(num[i]); 11 if(times == null) 12 hashtable.put(num[i], 1); 13 else{ 14 times = times + 1; 15 hashtable.put(num[i], times); 16 } 17 }//for 18 //遍历hash表 19 Iterator<Integer> it = hashtable.keySet().iterator(); 20 while(it.hasNext()){ 21 int key = it.next(); 22 if(hashtable.get(key) > num.length / 2){ 23 result = key; 24 break; 25 } 26 } 27 28 return result; 29 } 30 }
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原文地址：http://www.cnblogs.com/luckygxf/p/4180058.html
