Strip

题意翻译

给定一个长度为n的数组,要求把数组分为若干部分满足下面两个条件 (1):每个部分至少含有l个元素 (2):每个部分中两两数的差值的最大值不超过s 问在满足上述两个条件的情况下,最少能分成多少个部分。 $1\le n,l\le 10^5,1\le s\le 10^9$ $\forall 1\le i\le n, -10^9\le a_i\le 10^9$

题目描述

Alexandra has a paper strip with $ n $ numbers on it. Let's call them $ a_{i} $ from left to right. Now Alexandra wants to split it into some pieces (possibly $ 1 $ ). For each piece of strip, it must satisfy: - Each piece should contain at least $ l $ numbers. - The difference between the maximal and the minimal number on the piece should be at most $ s $ . Please help Alexandra to find the minimal number of pieces meeting the condition above.

输入输出格式

输入格式

Alexandra has a paper strip with $ n $ numbers on it. Let's call them $ a_{i} $ from left to right. Now Alexandra wants to split it into some pieces (possibly $ 1 $ ). For each piece of strip, it must satisfy: - Each piece should contain at least $ l $ numbers. - The difference between the maximal and the minimal number on the piece should be at most $ s $ . Please help Alexandra to find the minimal number of pieces meeting the condition above.

输出格式

Output the minimal number of strip pieces. If there are no ways to split the strip, output -1.

输入输出样例

输入样例 #1

7 2 2
1 3 1 2 4 1 2

输出样例 #1

3

输入样例 #2

7 2 2
1 100 1 100 1 100 1

输出样例 #2

-1

说明

Alexandra has a paper strip with $ n $ numbers on it. Let's call them $ a_{i} $ from left to right. Now Alexandra wants to split it into some pieces (possibly $ 1 $ ). For each piece of strip, it must satisfy: - Each piece should contain at least $ l $ numbers. - The difference between the maximal and the minimal number on the piece should be at most $ s $ . Please help Alexandra to find the minimal number of pieces meeting the condition above.