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UCV2013A - Counting Ids |
Little Willy just took a compilers course and is trying to implement his own compiler. First he wants to build a table with all the possible ids that a program could have. He knows that his language supports up to N different characters and any id can be up to L characters long. For example, when N = 2 (lets say characters can be 0 or 1), and L = 3, he could have the following ids: {0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111}.
You have to write a program that can help Willy find out the size of the table. Since the answer can be really big, you must print it modulo 1000000007 (10^9+7).
Input
The input contains several test cases. Each test case will consist of a single line containing two integers N and L. N is the number of characters that can be part of an id and L is maximum length supported by the language (1 <= N <= 65535, 1 <= L <= 10^5).
End of the input is indicated by a test case with N = 0, L = 0 that should not be processed.
Output
For each test case output a single line containing the number of possible ids modulo 10^9+7.
Example
Input: 2 3
128 32
0 0 Output: 14
792805767
Added by: | Hector Navarro |
Date: | 2013-07-22 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 |
Resource: | Local UCV 2013. Héctor Navarro |
hide comments
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2014-06-17 12:46:00 Amitayush Thakur
Weak test cases. Doesn't have a test case where N=1. |
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2014-01-05 20:53:42 যোবায়ের
Your input file should contain some cases where N = 1. Just saying... Last edit: 2014-01-05 20:54:08 |
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2013-09-13 08:06:40 Himanshu
@bigBOSS not a beginner problem learn a lot form this problem.... Last edit: 2013-09-13 08:15:34 |
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2013-08-02 01:19:28 Miguel Oliveira
@Degree of Freedom check http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm it explains the modular inverse |
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2013-08-01 18:16:14 Hitman
To my surprise O(L) works fine Last edit: 2013-08-01 18:16:38 |
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2013-08-01 06:48:39 Ouditchya Sinha
Easy but certainly not a tutorial problem, increased constraints could make it more challenging. :) |
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2013-07-31 16:15:31 narendray
Miguel Oliveira : Any link of Modular inverse regarding the algo. |
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2013-07-30 14:16:44 Anubhav Balodhi
What da?!? same code nzec in Python 3.2.3 but ac in python 2.7... |
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2013-07-29 13:51:09 abdelkarim
simple but nice math one ;) . |
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2013-07-29 13:22:57 mystique_blue
Akash your comment is a spoiler. Please remove it. Discuss in the forum. |