Time Limit: 10s
Memory Limit: 128MB
Halloween is coming! So xiaoY has to prepare M candies to treat the neighbor kids.
When this horrible night come, There are N little children ask xiaoY for candy, and each of them has different demand. For the i-th kid, his (or her) candy must not less than Min[i], and not greater than Max[i].
Now xiaoY wants to know how many ways he can give out all of his candies. (in case the large answer, please tell xiaoY the answer modular 10000007)
First line is an integer T, represents T cases followed:
N, M ---- Number of children, Number of candies.
(0<N<=20, 0<M<=10000)
Min[i], Max[i] ---- The lower bound and upper bound of I-th kid’s demand. (N lines)
(0<=Min[i] <= Max[i] <=M)
Output a number W which means total different ways of handing out the candies. (% 10000007)
2 3 5 1 2 1 2 1 2 3 6 1 2 1 2 1 2
Case #1: 3 Case #2: 1
For case 1, there are 3 ways to hand out:
1 + 2 + 2 = 5
2 + 1 + 2 = 5
2 + 2 + 1 = 5
For case 2, there is only one way to hand out:
2 + 2 + 2 = 6