magical
10^9 + 7.
Example 1:
Input: N = 1, A = 2, B = 3 Output: 2
Example 2:
Input: N = 4, A = 2, B = 3 Output: 6
Example 3:
Input: N = 5, A = 2, B = 4 Output: 10
Example 4:
Input: N = 3, A = 6, B = 4 Output: 8
Note:
Github 同步地址:
https://github.com/grandyang/leetcode/issues/878
参考资料：