letcode_1720.py

# There is a hidden integer array arr that consists of n non-negative integers.

# It was encoded into another integer array encoded of length n - 1, 
# such that encoded[i] = arr[i] XOR arr[i + 1]. For example, if arr = [1,0,2,1], then encoded = [1,2,3].

# You are given the encoded array. You are also given an integer first, that is the first element of arr,
#  i.e. arr[0].

# Return the original array arr. It can be proved that the answer exists and is unique.

# Example 1:

# Input: encoded = [1,2,3], first = 1
# Output: [1,0,2,1]
# Explanation: If arr = [1,0,2,1], then first = 1 and encoded = [1 XOR 0, 0 XOR 2, 2 XOR 1] = [1,2,3]
encoded = [1,2,3]
first = 1
result = [first]
j = len(encoded) + 1
cont = 0
n1 = 0
  
while True:
    if result[cont] ^ n1 != encoded[cont]:
        n1 +=1
    else:
        result.append(n1)
        cont +=1
        n1=0
        if len(result) == j:
            break
print(result)