250102 연산자 끼워넣기

private static class Result {
	int min;
	int max;

	Result(int min, int max) {
		this.min = min;
		this.max = max;
	}
}

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	int n = Integer.parseInt(br.readLine());
	int[] numbers = new int[n];
	int[] operators = new int[4];

	StringTokenizer st = new StringTokenizer(br.readLine());
	for (int i = 0; i < n; i++) {
		numbers[i] = Integer.parseInt(st.nextToken());
	}

	st = new StringTokenizer(br.readLine());
	for (int i = 0; i < 4; i++) {
		operators[i] = Integer.parseInt(st.nextToken());
	}

	Result result = new Result(Integer.MAX_VALUE, Integer.MIN_VALUE);
	calculate(numbers, operators, 1, numbers[0], result);

	System.out.println(result.max);
	System.out.println(result.min);
}

private static void calculate(int[] numbers, int[] operators, int idx, int current, Result result) {
	if (idx == numbers.length) {
		result.max = Math.max(result.max, current);
		result.min = Math.min(result.min, current);
		return;
	}

	for (int i = 0; i < 4; i++) {
		if (operators[i] > 0) {
			operators[i]--;
			int next = applyOperation(current, numbers[idx], i);
			calculate(numbers, operators, idx + 1, next, result);
			operators[i]++;
		}
	}
}

private static int applyOperation(int a, int b, int operator) {
	switch (operator) {
		case 0:
			return a + b;
		case 1:
			return a - b;
		case 2:
			return a * b;
		case 3:
			return a / b;
		default:
			throw new IllegalArgumentException("Invalid operator");
	}
}

출처:https://www.acmicpc.net/problem/14888