Leetcode #2191: Sort the Jumbled Numbers
In this guide, we solve Leetcode #2191 Sort the Jumbled Numbers in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
You are given a 0-indexed integer array mapping which represents the mapping rule of a shuffled decimal system. mapping[i] = j means digit i should be mapped to digit j in this system.
Quick Facts
- Difficulty: Medium
- Premium: No
- Tags: Array, Sorting
Intuition
Sorting reveals structure that is hard to see in the original order.
Once sorted, a linear scan is usually enough to compute the answer.
Approach
Sort the data and sweep through it while maintaining a small state.
This keeps the logic straightforward and reliable.
Steps:
- Sort the data.
- Scan in order while maintaining state.
- Update the best answer.
Example
Input: mapping = [8,9,4,0,2,1,3,5,7,6], nums = [991,338,38]
Output: [338,38,991]
Explanation:
Map the number 991 as follows:
1. mapping[9] = 6, so all occurrences of the digit 9 will become 6.
2. mapping[1] = 9, so all occurrences of the digit 1 will become 9.
Therefore, the mapped value of 991 is 669.
338 maps to 007, or 7 after removing the leading zeros.
38 maps to 07, which is also 7 after removing leading zeros.
Since 338 and 38 share the same mapped value, they should remain in the same relative order, so 338 comes before 38.
Thus, the sorted array is [338,38,991].
Python Solution
class Solution:
def sortJumbled(self, mapping: List[int], nums: List[int]) -> List[int]:
def f(x: int) -> int:
if x == 0:
return mapping[0]
y, k = 0, 1
while x:
x, v = divmod(x, 10)
v = mapping[v]
y = k * v + y
k *= 10
return y
arr = sorted((f(x), i) for i, x in enumerate(nums))
return [nums[i] for _, i in arr]
Complexity
The time complexity is , and the space complexity is . The space complexity is .
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.