双端队列

双端队列

1. 求解连续数列

# 用例
7611 86

import java.util.Scanner;
import java.util.*;


// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String[] split = in.nextLine().split(" ");
        int sum = Integer.parseInt(split[0]);
        int count = Integer.parseInt(split[1]);
        Deque<Integer> deque = new ArrayDeque<>();
        int temp = 0;
        for (int i = 1; i <= count;i++) {  //  【1，86】
            deque.add(i);
            temp += i;
        }
        if (temp == sum){  //  判断前 k 个是否已经是答案
            StringBuilder sb = new StringBuilder();
            for (int i = 1; i <= count; i++) {
                sb.append(i + " ");
            }
            System.out.println(sb.toString().trim());
            return;
        }

        for (int i = count + 1; i < 100000; i++) {  //  这里从 87 开始了，所以 count + 1
            Integer first = deque.removeFirst();
            deque.add(i);
            temp = temp - first + i;
            if (temp > sum){
                System.out.println(-1);
                return;
            }
            if (temp == sum){
                StringBuilder sb = new StringBuilder();
                for (int j = i - count + 1; j <= i; j++) {
                    sb.append(j + " ");
                }
                System.out.println(sb.toString().trim());
                return;
            }
        }
        System.out.println(-1);

    }
}