Leetcode 229. Majority Element II

文章作者：Tyan
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1. Description

Majority Element II

2. Solution

• Version 1

class Solution {
public:
    vector majorityElement(vector& nums) {
        int limit = nums.size() / 3;
        vector result;
        unordered_map m;
        for(int num : nums) {
            m[num]++;
            if(m[num] > limit) {
                m[num] = INT_MIN;
                result.push_back(num);
            }
        }
        return result;
    }
};

• Version 2

class Solution {
public:
    vector majorityElement(vector& nums) {
        vector result;
        int limit = nums.size() / 3;
        int candidate1 = 0, candidate2 = 0;
        int count1 = 0, count2 = 0;
        for(int num : nums) {
            if(num == candidate1) {
                count1++;
            }
            else if(num == candidate2) {
                count2++;
            }
            else if(count1 == 0) {
                candidate1 = num;
                count1 = 1;
            }
            else if(count2 == 0) {
                candidate2 = num;
                count2 = 1;
            }
            else {
                count1--;
                count2--;
            }
        }
        count1 = 0;
        count2 = 0;
        for(int num : nums) {
            if(num == candidate1) {
                count1++;
            }
            else if(num == candidate2) {
                count2++;
            }
        }
        if(count1 > limit) {
            result.push_back(candidate1);
        }
        if(count2 > limit) {
            result.push_back(candidate2);
        }
        return result;
    }
};

Reference

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