求数组的所有排列组合数

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于 2017-12-06 16:07:45 发布 · 1.5k 阅读

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#排列组合算法

给定一个序列S，例如{1, 2, 3}，求解其中非递减子序列的数量。输入包含序列长度n（1 <= n <= 100000）和序列本身，输出所有非递减子序列数量对1000000007取模的结果。样例输入为序列长度3及序列{1, 2, 3}，输出应为7。" 108857932,9211270,HALCON差异模板在打印质量检测中的应用,"['计算机视觉', '图像处理', '机器学习', '模板匹配', '自动化检测']

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Problem Description
How many nondecreasing subsequences can you find in the sequence S = {s1, s2, s3, …., sn} ? For example, we assume that S = {1, 2, 3}, and you can find seven nondecreasing subsequences, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}.
Input
The input consists of multiple test cases. Each case begins with a line containing a positive integer n that is the length of the sequence S, the next line contains n integers {s1, s2, s3, …., sn}, 1 <= n <= 100000, 0 <= si <= 2^31.
Output
For each test case, output one line containing the number of nondecreasing subsequences you can find from the sequence S, the answer should % 1000000007.
Sample Input
3
1 2 3
Sample Output
7

代码：

static List<String> list = new ArrayList<String>();
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