#P1118. [USACO06FEB] Backward Digit Sums G/S
[USACO06FEB] Backward Digit Sums G/S
题目描述
FJ
and his cows enjoy playing a mental game. They write down the numbers from to in a certain order and then sum adjacent numbers to produce a new list with one fewer number. They repeat this until only a single number is left. For example, one instance of the game (when ) might go like this:
3 1 2 4
4 3 6
7 9
16
Behind FJ
's back, the cows have started playing a more difficult game, in which they try to determine the starting sequence from only the final total and the number . Unfortunately, the game is a bit above FJ
's mental arithmetic capabilities.
Write a program to help FJ
play the game and keep up with the cows.
有这么一个游戏:
写出一个至的排列,然后每次将相邻两个数相加,构成新的序列,再对新序列进行这样的操作,显然每次构成的序列都比上一次的序列长度少,直到只剩下一个数字位置。下面是一个例子:
最后得到这样一个数字。
现在想要倒着玩这样一个游戏,如果知道,知道最后得到的数字的大小,请你求出最初序列,为至的一个排列。若答案有多种可能,则输出字典序最小的那一个。
管理员注:本题描述有误,这里字典序指的是
而不是
输入格式
两个正整数。
输出格式
输出包括行,为字典序最小的那个答案。
当无解的时候,请什么也不输出。(好奇葩啊)
4 16
3 1 2 4
提示
对于的数据,;
对于的数据,;
对于的数据,。