Leetcode 169. Majority Element

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最新推荐文章于 2024-01-03 12:37:31 发布

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分类专栏： bitManipulation Leetcode

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本文介绍了几种方法来解决数组中找到出现次数超过一半的元素的问题，包括哈希表、投票法和位操作方法。

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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.

Analysis:

There are many methods for this question.

1 HashTable

2 Vote method.

3 Bit manipulation;

vote method code

public class Solution {

    public int majorityElement(int[] nums) {
      int length = nums.length;
      if(length == 1)
        return nums[0];
      int tem = nums[0];
      int number = 1;
      for(int i = 1; i < length;i++){
        if(nums[i] != tem)
        {
          if(number == 1){
            tem = nums[i];
            number = 1;
          }
          else{
            number--;
          }
        }
        else{
          number++;
        }
      }
      return tem;
    }
}

3 Bit manipulation method: just to count the number of 1 bit for every position: if the number of 1 for specific position is larger than numberOfArray/2, it must belongs to the majority number