9. 뮤직비디오(결정알고리즘)

import java.util.*;

class Main {

	public int count(int m, int[] arr) {
		int cnt = 1;
		int sum = 0;
		int tmp = 0;
		for (int i = 0; i < arr.length; i++) {
			tmp = sum + arr[i];
			if (tmp <= m) {
				sum = tmp;
			} else {
				sum = arr[i];
				cnt++;
			}
		}
		return cnt;
	}

	public int solution(int N, int M, int[] arr) {
		int answer = Integer.MAX_VALUE;
		int lt = 1, rt = 0, mid = 0;
		for (int x : arr)
			rt += x;
		while (lt <= rt) {
			mid = (lt + rt) / 2;
			int cnt = count(mid, arr);
			if (cnt <= M) {
				rt--;
				if (mid < answer) {
					answer = mid;
				}
			} else if (cnt > M) {
				lt = mid + 1;
			} else if (cnt < M) {
				rt = mid - 1;
			}
		}
		return answer;
	}

	public static void main(String[] args) {
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		int N = kb.nextInt();
		int M = kb.nextInt();
		int[] arr = new int[N];
		for (int i = 0; i < N; i++)
			arr[i] = kb.nextInt();
		System.out.print(T.solution(N, M, arr));
		kb.close();
	}
}

 

import java.util.*;

class Main {

	public int count(int[] arr, int capacity) {
		int cnt = 1, sum = 0;
		for (int x : arr) {
			if (sum + x > capacity) {
				cnt++;
				sum = x;
			} else
				sum += x;
		}
		return cnt;
	}

	public int solution(int N, int M, int[] arr) {
		int answer = 0;
		int lt = Arrays.stream(arr).max().getAsInt();
		int rt = Arrays.stream(arr).sum();
		while (lt <= rt) {
			int mid = (lt + rt) / 2;
			if (count(arr, mid) <= M) {
				answer = mid;
				rt = mid - 1;
			} else
				lt = mid + 1;
		}
		return answer;
	}

	public static void main(String[] args) {
		Main T = new Main();
		Scanner kb = new Scanner(System.in);
		int N = kb.nextInt();
		int M = kb.nextInt();
		int[] arr = new int[N];
		for (int i = 0; i < N; i++)
			arr[i] = kb.nextInt();
		System.out.print(T.solution(N, M, arr));
		kb.close();
	}
}

stream 사용법 기억해두기

		int lt = Arrays.stream(arr).max().getAsInt();
		int rt = Arrays.stream(arr).sum();