acwing 4862. 浇花 （前缀和） java

🤠 原题链接
🤠 避坑：花一天可以浇 n 次，不仅仅是 0 1 2

import java.util.*;
public class Main
{
	static int N = (int) 1e5 + 10;
	static int[] A = new int[N];// 差分数组
	static int[] B = new int[N];// 前缀和数组

	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();// 假期天数
		int m = sc.nextInt();// 人数

		for (int i = 0; i < m; i++)
		{
			int a = sc.nextInt();
			int b = sc.nextInt();
			A[a] += 1;
			A[b + 1] -= 1;
		}

		for (int i = 1; i <= n; i++)
		{
			B[i] = A[i] + B[i - 1];
		}
		int k = 1;
		for (k =1; k <= n; k++)
		{
			if (B[k] == 0 || B[k] == 2)
			{
				System.out.print(k + " " + B[k]);
				break;
			}
		}
		if (k == n+1)
			System.out.print("OK");

	}
}