MediumNo. 1734
Decode XORed Permutation — LeetCode 1734 Python Solution
- Pattern
- Bit Manipulation
- Topics
- Bit Manipulation, Array
- Reading time
- 2 min
- Source
- leetcode.com
The problem
There is an integer array perm that is a permutation of the first n positive integers, where n is always odd. It was encoded into another integer array encoded of length n - 1, such that encoded[i] = perm[i] XOR perm[i + 1].
Example
- Input
- encoded = [3,1]
- Output
- [1,2,3]
- Explanation
- If perm = [1,2,3], then encoded = [1 XOR 2,2 XOR 3] = [3,1]
Python solution
class Solution:
def decode(self, encoded: List[int]) -> List[int]:
n = len(encoded) + 1
a = b = 0
for i in range(0, n - 1, 2):
a ^= encoded[i]
for i in range(1, n + 1):
b ^= i
perm = [0] * n
perm[-1] = a ^ b
for i in range(n - 2, -1, -1):
perm[i] = encoded[i] ^ perm[i + 1]
return permComplexity
- Time
- O(n)where n is the length of the array perm
- Space · auxiliary
- O(1)
Pattern: Bit Manipulation
Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 1734. Decode XORed Permutation is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.
The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.
Related problems
| No. | Problem | Difficulty |
|---|---|---|
| 0136 | Single Number | Easy |
| 0137 | Single Number II | Medium |
| 0260 | Single Number III | Medium |
| 0287 | Find the Duplicate Number | Medium |
| 0318 | Maximum Product of Word Lengths | Medium |
| 0393 | UTF-8 Validation | Medium |
Frequently asked questions
- How hard is LeetCode 1734. Decode XORed Permutation?
LeetCode 1734. Decode XORed Permutation is rated Medium on LeetCode.
- What is the time complexity of LeetCode 1734. Decode XORed Permutation?
The Python solution on this page runs in O(n), where n is the length of the array perm.
- What is the space complexity of LeetCode 1734. Decode XORed Permutation?
The Python solution on this page uses O(1) auxiliary space.
- What topics does LeetCode 1734. Decode XORed Permutation cover?
LeetCode 1734. Decode XORed Permutation is tagged Bit Manipulation and Array on LeetCode.