[C++] 백준 2805번 나무 자르기

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

const int MAX = 1000000;
long long arr[MAX];
long long M;
int N;

bool can(long long height) {
	long long len = 0;
	for (int i = 0; i < N; i++) {
		if (arr[i] - height > 0)
			len += arr[i] - height;
	}

	if (len >= M)
		return true;
	else
		return false;
}


int main() {

	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	cin >> N >> M;
	long long low = 1, high = 0;

	for (int i = 0; i < N; i++) {
		cin >> arr[i];
		high = max(high, arr[i]);
	}

	long long result = 0;

	while (low <= high) {
		long long mid = (low + high) / 2;
		if (can(mid)) {
			result = max(result, mid);
			low = mid + 1;
		}
		else {
			high = mid - 1;
		}
	}

	cout << result << "\n";


	return 0;
}