[백준] - 2805/나무자르기

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import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.*;

public class Main_2805 {

	public static void main(String[] args) throws FileNotFoundException {
		System.setIn(new FileInputStream("src/input.txt"));
		Scanner sc = new Scanner(System.in);
		int N= sc.nextInt();
		int M=sc.nextInt();
		int[] arr= new int[N];
		for(int i=0;i<N;i++) {
			arr[i]=sc.nextInt();
		}
		Arrays.sort(arr);
		int ans=0;
		
		long sum=0;
		int start=0;
		int end=arr[N-1];
		while(true) {
			int middle=(start+end)/2;
			sum=0;
			for(int i=0;i<N;i++) {
				long tmp = arr[i]-middle;
				if(tmp>=0) {
					sum+=tmp;
				}
			}
			if(sum>=M) {
				start=middle+1;
			}else if(sum<M) {
				end=middle-1;
			}
			if(start>end) {
				break;
			}
		}
		System.out.println(end);
	}
}