# Program to decrypt code to defuse the bomb in Python

Suppose there is a bomb that you are going to defuse, and your time is running out! You have a a circular array code of length of n and have a key k. Now to decrypt the code, you must replace every number. All the numbers are replaced simultaneously. There are few rules −

• If k > 0 then replace ith number with the sum of next k numbers.

• If k < 0 then replace ith number with the sum of previous k numbers.

• If k = 0 then replace ith number with 0.

Here the code is circular, so the next element of code[n-1] is code[0], and the previous element of code[0] is code[n-1]. Finally we have to return the decrypted code.

So, if the input is like code = [8,2,3,5], k = 3, then the output will be [10, 16, 15, 13], because, for each key we replace with next three elements sum, so code[0] will be 10, code[1] will be 16, code[2] will be 15 and code[3] will be 13.

To solve this, we will follow these steps &mius;

• decode := a new list

• for i in range 0 to size of code - 1, do

• if k > 0, then

• sum := 0

• j := i+1

• m := k

• while m is non-zero, do

• sum := sum + code[j mod length of code]

• m := m - 1

• j := j + 1

• insert sum at the end of decode

• otherwise when k is same as 0, then

• insert 0 at the end of decode

• otherwise,

• sum := 0

• j := i-1

• m := k

• while m is non-zero, do

• sum := sum + code[j mod length of code]

• m := m + 1

• j := j - 1

• insert sum at the end of decode

• return decode

## Example (Python)

Let us see the following implementation to get better understanding −

Live Demo

def solve(code, k):
decode = []
for i in range(len(code)):
if k > 0:
sum = 0
j = i+1
m = k
while(m):
sum+=code[j%len(code)]
m-=1
j+=1
decode.append(sum)

elif k == 0:
decode.append(0)

else:
sum = 0
j = i-1
m = k
while(m):
sum+=code[j%len(code)]
m+=1
j-=1
decode.append(sum)

return decode

code = [8,2,3,5]
k = 3
print(solve(code, k))

## Input

[8,2,3,5], 3

## Output

[10, 16, 15, 13]