Score : 1200 points
You are given a permutation of 1,2,...,N: p_1,p_2,...,p_N. Determine if the state where p_i=i for every i can be reached by performing the following operation any number of times:
Input is given from Standard Input in the following format:
N p_1 : p_N
If the state where p_i=i for every i can be reached by performing the operation, print Yes
; otherwise, print No
.
5 5 2 1 4 3
Yes
The state where p_i=i for every i can be reached as follows:
4 3 2 4 1
No
7 3 2 1 6 5 4 7
Yes
6 5 3 4 1 2 6
No