프로그래머스 시소 짝궁 (JAVA)

https://school.programmers.co.kr/learn/courses/30/lessons/152996

프로그래머스

 

 

import java.util.*;
class Solution {
    public long solution(int[] weights) {
        long answer = 0;
        Map<Integer,Integer> cnt = new HashMap<>();
        for(int weight : weights){
            cnt.merge(weight,1,(v1,v2)->{
                return v1+1;
            });
        }
        for(int key : cnt.keySet()){
            long nowCnt = cnt.getOrDefault(key,0);
            if(nowCnt == 0){
                continue;
            }
            answer += nowCnt * (nowCnt - 1) / 2;
            int tempCnt = 0;
            if(4 * key % 3 == 0){
                tempCnt = cnt.getOrDefault((int)((4 * key) / 3),0);
                answer += nowCnt * tempCnt;
            }
            if(3 * key % 2 == 0){
                tempCnt = cnt.getOrDefault((int)((3 * key) / 2),0);
                answer += nowCnt * tempCnt;
            }
            tempCnt = cnt.getOrDefault((2*key),0);
            answer += nowCnt * tempCnt;
            // System.out.println(key + " " + answer);
        }
        return answer;
    }
}