CT14E - Camels
Bob likes to draw camels: with a single hump, two humps, three humps, etc. He draws a camel by connecting points on a coordinate plane. Now he's drawing camels with t humps, representing them as polylines in the plane. Each polyline consists of n vertices with coordinates (x1, y1), (x2, y2), ... (xn, yn). The first vertex has a coordinate x1 = 1, the second x2 = 2, etc. Coordinates yi might be any, but should satisfy the following conditions:
- there should be t humps precisely, i.e. such indexes j (2 ≤ j ≤ n - 1), so that yj - 1 < yj > yj + 1,
- there should be precisely t - 1 such indexes j (2 ≤ j ≤ n - 1), so that yj - 1 > yj < yj + 1,
- no segment of a polyline should be parallel to the Ox-axis,
- all yi are integers between 1 and 4.
For a series of his drawings of camels with t humps Bob wants to buy a notebook, but he doesn't know how many pages he will need. Output the amount of different polylines that can be drawn to represent camels with t humps for a given number n.
Input
The first line of input contains the number of test cases, N.
Each test case contains a pair of integers n and t (3 ≤ n ≤ 20, 1 ≤ t ≤ 10).
Output
For each testcase, output the required number of camels with t humps.
Example
Input: 1 6 1 Output: 6
Note In the first sample test sequences of y-coordinates for six camels are: 123421, 123431, 123432, 124321, 134321 and 234321 (each digit corresponds to one value of yi).
hide comments
joeon:
2021-08-02 17:54:29
The fact is you really need to check the title |
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Phan Công Minh:
2010-06-03 01:41:01
Thanks . I've fixed the error. |
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Jorge Bernadas:
2010-06-03 01:40:54
No, really you have to check your sample input, it should be:
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AM_PM:
2010-06-03 01:40:54
Please check the limits in the input file ! Last edit: 2010-06-02 19:16:59 |
Added by: | Phan Công Minh |
Date: | 2010-06-02 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: NODEJS OBJC PERL6 SQLITE VB.NET |
Resource: | Codeforces. |