[LeetCode][JavaScript]Majority Element II

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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.

https://leetcode.com/problems/majority-element-ii/

 

 

 

 

使用Moore voting algorithm，時間複雜度是O(3n)，空間複雜度是O(1)。

 1 /** 2  * @param {number[]} nums 3  * @return {number[]} 4  */ 5 var majorityElement = function(nums) { 6     var i = 0, res = null, trinity = [], curr = null;  7     var result = []; 8     for(i = 0; i < nums.length; i++){ 9         curr = nums[i];10         res = isInTrinity(curr, trinity);11         if(res !== -1){12             trinity[res].count++;13         }else{14             if(trinity.length <= 1){15                 trinity.push({key : curr, count : 1});16             }else{17                 trinity[1].count--;18                 if(trinity[1].count === 0){19                     trinity.pop();20                 }21                 trinity[0].count--;22                 if(trinity[0].count === 0){23                     trinity.shift();24                 }25             }26         }27     }    28     if(trinity[0]){29         verifyNum(trinity[0].key, result);30     }31     if(trinity[1]){32         verifyNum(trinity[1].key, result);33     }34     return result;35     36     function verifyNum(num, result){37         var count = 0;38         for(i = 0; i < nums.length; i++){39             if(nums[i] === num){40                 count++;41             }42         }43         if(count > nums.length / 3){44             result.push(num);45         }46     }47     function isInTrinity(num, trinity){48         for(var i = 0; i < trinity.length; i++){49             if(trinity[i].key === num){50                 return i;51             }52         }53         return -1;54     }55 };

 

 

 

   

[LeetCode][JavaScript]Majority Element II