240327 가장 많이 받은 선물

public int solution(String[] friends, String[] gifts) {
    int n = friends.length;
	int[][] history = new int[n][n];
	int[] giftScore = new int[n];
	int[] nextMonthGift = new int[n];

	HashMap<String, Integer> friendIndex = new HashMap<>();
	for (int i = 0; i < n; i++) {
		friendIndex.put(friends[i], i);
	}

	for (String gift : gifts) {
		String[] tmp = gift.split(" ");
		int giverIndex = friendIndex.get(tmp[0]);
		int takerIndex = friendIndex.get(tmp[1]);

		history[giverIndex][takerIndex]++;

		giftScore[giverIndex]++;
		giftScore[takerIndex]--;
	}

	for (int giver = 0; giver < n; giver++) {
		for (int taker = giver + 1; taker < n; taker++) {
			int give = history[giver][taker];
			int take = history[taker][giver];

			if (give > take) {
				nextMonthGift[giver]++;
			} else if (give < take) {
				nextMonthGift[taker]++;
			} else {
				if (giftScore[giver] > giftScore[taker]) {
					nextMonthGift[giver]++;
				} else if (giftScore[giver] < giftScore[taker]) {
					nextMonthGift[taker]++;
				}
			}
		}
	}

	return Arrays.stream(nextMonthGift)
			.max()
			.getAsInt();
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/258712