IOI '08 - Cairo, Egypt
Ramesses II has just returned victorious from battle. To commemorate his victory, he has decided to build a majestic garden. The garden will contain a long line of plants that will run all the way from his palace at Luxor to the temple of Karnak. It will consist only of lotus plants and papyrus plants, since they symbolize Upper and Lower Egypt respectively.
The garden must contain exactly N plants. Also, it must be balanced: in any contiguous section of the garden, the numbers of lotus and papyrus plants must not differ by more than 2.
A garden can be represented as a string of letters 'L' (lotus) and 'P' (papyrus). For example, for N=5 there
are 14 possible balanced gardens. In alphabetical order, these are:
The possible balanced gardens of a certain length can be ordered alphabetically, and then numbered
starting from 1. For example, for N=5, garden number 12 is the garden
Write a program that, given the number of plants N and a string that represents a balanced garden, calculates the number assigned to this garden modulo some given integer M.
Note that for solving the task, the value of M has no importance other than simplifying computations.
Your program must read from the standard input the following data:
- Line 1 contains the integer N (1 ≤ N ≤ 1 000 000), the number of plants in the garden.
- Line 2 contains the integer M (7 ≤ M ≤ 10 000 0000).
- Line 3 contains a string of N characters 'L' (lotus) or 'P' (papyrus) that represents a balanced garden.
Your program must write to the standard output a single line containing one integer between 0 and M-1 (inclusive), the number assigned to the garden described in the input, modulo M.
Sample Input 1
5 7 PLPPL
Sample Output 1
The actual number assigned to
PLPPL is 12. So, the output is 12 modulo 7, which is 5.
Sample Input 2
12 10000 LPLLPLPPLPLL
Sample Output 2
Note: In test cases worth a total of 40% of the points, N will not exceed 40.
Point Value: 20 (partial)
Time Limit: 1.50s
Memory Limit: 128M
Added: Jun 02, 2010
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