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ITRIX12E - R Numbers |
R - Numbers
R-numbers are numbers which have the property that they do not have the digit '0' and sum of every two adjacent digits of the number is prime. 123 is a R-number because 1+2 =3 and 2+3 =5 and 3, 5 are primes.
How many R-numbers can be formed with at most length N?
i.e. R-numbers of length 1 + R-numbers of length 2 + R-numbers of length 3 + ... R-numbers of length N.
Length of a number = Number of digits in the number.
Only four single digit numbers are R-numbers which are nothing but single digit primes 2, 3, 5, 7.
Input Specification
The first line of the input file contains T which denotes the number of test cases. The next T lines contain an integer N <= 10^9.
Output Specification
Print the numbers of R-numbers modulo 1000000007. [10^9+7];
Example
Sample Input: 2 1 2 Sample Output: 4 33
Added by: | Radhakrishnan Venkataramani |
Date: | 2012-03-12 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 |
Resource: | Own problem |
hide comments
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2024-11-14 20:35:18
@ harshit2202 Add another row and column to the transition matrix and one row to the base matrix. In the added cell in the base matrix you can accumulate the sum of answers for all possible digit numbers up to N by making the transition matrix add all the values of the base matrix together and put the result in the mentioned cell (You can for example fill the added row in the transition matrix with 1s). |
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2023-06-23 06:33:16
Can someone help me why its giving run time and what is better optimisation for this solution <snip> [Simes]: this is not the place for a code review, use the forum. Last edit: 2023-06-23 08:09:50 |
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2021-07-20 13:30:31
Used G.P. sum with common ratio in the form of matrix. |
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2019-03-16 08:41:34
I can find it for particular N in log N How to find it for atmost N because is N is too large |
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2018-10-07 09:41:51
Amazing problem , solved using linear recurrence relation :) |
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2018-09-08 14:40:48
ONE HELL OF A QUESTION |
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2018-08-23 17:36:48
(correct) answers for a few values of n: 1: 4 2: 33 3: 130 4: 454 5: 1545 10: 663370 100: 26514125 1000: 906016252 10000: 396515823 100000: 827019605 1000000: 294370820 10000000: 29572369 100000000: 530109085 1000000000: 757510247 |
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2016-06-03 09:16:25
NICE QUESTION LEARNT A LOT |
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2016-05-15 08:59:27 harkirat
@david : wrong |
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2013-09-24 20:17:39 David
Sorry - my bad and WA at the time. IP: 3 3 4 5 OP: 130 454 1545 Last edit: 2021-04-06 19:23:47 |