[BOJ] 2805. 나무 자르기

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		int[] arr = new int [N];
		
		for(int i = 0; i < arr.length; i++) {
			arr[i] = sc.nextInt();			
		}
		
		Arrays.sort(arr);
		
		int left = 0;
		int right = arr[N - 1];
		int answer = 0;
		while(left <= right) {
			int mid = (left + right) / 2;
			if(isOK(arr, mid, M)) {
				answer = Math.max(answer, mid);
				left = mid + 1;
			} else {
				right = mid - 1;
			}
		}
		
		System.out.println(answer);
				
	}
	public static boolean isOK(int[] arr, int mid, int M) {
		for(int i = 0; i < arr.length; i++) {
			if(arr[i] <= mid) continue;
			else M = M - (arr[i] - mid);
			
			if(M <= 0) return true;
		}
		return false;
	}
}