229. Majority Element II

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題目敘述

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times.

Example 1

Input: nums = [3,2,3] Output: [3]

Example 2

Input: nums = [1] Output: [1]

Example 3

Input: nums = [1,2] Output: [1,2]

解題思路

Solution

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class Solution {
    public List<Integer> majorityElement(int[] nums) {
        List<Integer> ans = new ArrayList<>();
        Map<Integer, Integer> map = new HashMap<>();
        int up = nums.length / 3;

        for(int num : nums){
            map.put(num, map.getOrDefault(num, 0) + 1);
        }

        for(int key : map.keySet()){
            if(map.get(key) > up){
                ans.add(key);
            }
        }

        return ans;
    }
}