ABCD  Colours A, B, C, D
Consider a table with 2 rows and 2N columns (a total of 4N cells). Each cell of the first row is coloured by one of the colours A, B, C, D such that there are no two adjacent cells of the same colour. You have to colour the second row using colours A, B, C, D such that:
• There are exactly N cells of each colour (A, B, C and D) in the table.
• There are no two adjacent cells of the same colour. (Adjacent cells share a vertical or a horizontal side.)
It is guaranteed that the solution, not necessarily unique, will always exist.
Input
[a natural number N ≤ 50000]
[a string of 2N letters from the set {A, B, C, D}, representing the first row of the table]
Output
[a string of 2N letters from the set {A, B, C, D}, representing the second row of the table]
Example
Input
1
CB
Output
AD
Input
2
ABAD
Output
BCDC
hide comments
(Tjandra Satria Gunawan)(æ›¾æ¯…æ˜†):
20150802 04:25:08
Finally AC, it's hard to think the solution but very easy to implement :) 

Shubhransh Srivastav:
20150709 17:10:53
wa on running judge 18.... don't know why :( Last edit: 20150713 19:30:43 

Diksha Jaiswal:
20150604 07:37:37
tle with backtracking :( 

Aman:
20150530 20:23:24
I think all possible permutations are not considered in the solution that's why its giving wrong ans on 18th test case... can any tell me what is 18th case.I have tried all possible test cases...can't find the error.... 

CoNtRaDiCtIoN:
20150527 12:31:32
awesome problem :) 

Rajat (1307086):
20150328 00:56:52
There are several solutions, but if you apply the correct logic you will get one and only one.


chamini2:
20150213 23:46:34
It's not test 18, it's wrong answer in general. 

Malinga:
20141225 16:23:20
Getting wrong answer in 18th test case...any suggestions please ?? 

Anubhav Balodhi :
20141218 14:10:04
got AC, after lot of tries :) 

Retaliation:
20141207 07:40:41
I got an internal error while submitting the code in python.

Added by:  Adrian Satja Kurdija 
Date:  20110313 
Time limit:  0.190s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel Pentium G860 3GHz) 
Languages:  All 
Resource:  originated from a mathematical problem 