21 人解决，35 人已尝试。
27 份提交通过，共有 148 份提交。
5.7 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
In how many ways can you choose k elements out of n elements, not taking order into account?
Write a program to compute this number.
The input will contain one or more test cases.
Each test case consists of one line containing two integers n (n>=1) and k (0<=k<=n).
Input is terminated by two zeroes for n and k.
For each test case, print one line containing the required number. This number will always fit into an integer, i.e. it will be less than 2^31.
Warning: Don’t underestimate the problem. The result will fit into an integer - but if all intermediate results arising during the computation will also fit into an integer depends on your algorithm. The test cases will go to the limit.
4 2 10 5 49 6 0 0
6 252 13983816