[코테 풀이] Maximum Number of Pairs in Array

Q_2341) Maximum Number of Pairs in Array

출처 : https://leetcode.com/problems/maximum-number-of-pairs-in-array/

You are given a 0-indexed integer array nums. In one operation, you may do the following:

• Choose two integers in nums that are equal.
• Remove both integers from nums, forming a pair.

The operation is done on nums as many times as possible.

Return a 0-indexed integer array answer of size 2 where answer[0] is the number of pairs that are formed and answer[1] is the number of leftover integers in nums after doing the operation as many times as possible.

class Solution {
    public int[] numberOfPairs(int[] nums) {
        int count = 0;
        ArrayList<Integer> arrayList = new ArrayList<>();
        for (int i : nums) arrayList.add(i);
        int j = 0;
        int k = j + 1;
        boolean flag = true;
        while (flag) {
            if (arrayList.size() == 1) return new int[]{count, 1};
            if (arrayList.size() == 0) return new int[]{count, 0};
            if (arrayList.get(j) == arrayList.get(k)) {
                count++;
                arrayList.remove(j);
                arrayList.remove(k - 1);
                j = 0; //다시 처음부터 iterate
                k = j + 1; //바로 옆 index를 가진 숫자와 비교
            } else {
                k++; //비교할 대상 바꾸기
            }
            if (k == arrayList.size()) {
                j++; //비교할 대상 내내 찾다가 pair를 못 찾았을 경우
                if(j+1 >= arrayList.size()) break;
                else k = j + 1;
            }

        }
        return new int[]{count, arrayList.size()};
    }
}