ACODE - Alphacode

Alice and Bob need to send secret messages to each other and are discussing ways to encode their messages:

Alice: “Let’s just use a very simple code: We’ll assign ‘A’ the code word 1, ‘B’ will be 2, and so on down to ‘Z’ being assigned 26.”

Bob: “That’s a stupid code, Alice. Suppose I send you the word ‘BEAN’ encoded as 25114. You could decode that in many different ways!”

Alice: “Sure you could, but what words would you get? Other than ‘BEAN’, you’d get ‘BEAAD’, ‘YAAD’, ‘YAN’, ‘YKD’ and ‘BEKD’. I think you would be able to figure out the correct decoding. And why would you send me the word ‘BEAN’ anyway?”

Bob: “OK, maybe that’s a bad example, but I bet you that if you got a string of length 5000 there would be tons of different decodings and with that many you would find at least two different ones that would make sense.”

Alice: “How many different decodings?”

Bob: “Jillions!”

For some reason, Alice is still unconvinced by Bob’s argument, so she requires a program that will determine how many decodings there can be for a given string using her code.


Input will consist of multiple input sets. Each set will consist of a single line of at most 5000 digits representing a valid encryption (for example, no line will begin with a 0). There will be no spaces between the digits. An input line of ‘0’ will terminate the input and should not be processed.


For each input set, output the number of possible decodings for the input string. All answers will be within the range of a 64 bit signed integer.






hide comments
divyansh_soni: 2018-08-11 15:14:56

forgot to check for "01" like decoding
Got WA
then cheked it...
Got AC

Last edit: 2018-08-11 15:18:55
aaryan6600: 2018-08-03 11:27:28

i got AC on HackerEarth and WA here for the same code. How so >?

jason_chatz: 2018-07-31 18:36:03

C++ didn't cause me any problem with standard memoization, I am sorry some others experienced problems.

maruf_robin: 2018-07-30 19:21:57

handle 10 and 20

fr0zen: 2018-07-19 01:04:02

@coder579: "1001" is not a valid encryption.
- 1,0,0,1 <- Invalid
- 10,0,1 <- Invalid
- 10,01 <- Invalid
- 1,0,01 <- Invalid

coder579: 2018-07-16 10:48:19

If you are getting WA, check for:

trump23: 2018-07-12 13:30:52

@ankur314 Thank You! your test case is brilliant

himanshu1216: 2018-07-07 22:11:41

@ankur314 thanks man. That saved a lot of trouble

redcenturion: 2018-07-04 18:37:20

Last edit: 2018-07-04 19:15:37
summer_2: 2018-06-22 21:36:45

Wasted 3 hrs on C++ it gives Runtime SIGSEGV error
same logic submitted using Python!
Prefer Python for this problem!

Added by:Adrian Kuegel
Time limit:0.5s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Resource:ACM East Central North America Regional Programming Contest 2004