Is Shuffle String easy or hard?

Shuffle String is classified as an Easy problem on LeetCode with a high acceptance rate of around 85%. The challenge mainly checks whether you recognize the direct index mapping and implement a linear-time reconstruction.

How to solve Shuffle String in O(n)?

Create a character array of the same length as the input string. Loop through the indices array, and place s[i] into result[indices[i]]. After filling all positions, convert the array to a string. Each element is handled once, giving O(n) time complexity.

What is the best approach for Shuffle String?

The best approach is array construction. Iterate through the string once and place each character s[i] at position indices[i] in a new result array. This solution runs in O(n) time with O(n) space and is the most straightforward method expected in coding interviews.

What data structure is used in Shuffle String?

The main data structure is an array (or character array). The indices array acts as a mapping that determines where each character should move in the final string. No advanced structures like hash maps or trees are required.

What is the time complexity of Shuffle String?

The optimal solution runs in O(n) time because each character is processed exactly once. A result array is filled using direct index mapping from the indices array. Space complexity is O(n) for storing the reconstructed string.

Shuffle String Python or Java solution approach?

Both Python and Java solutions follow the same logic: allocate a result array, iterate through the string, and assign result[indices[i]] = s[i]. Python often uses a list of characters before joining into a string, while Java uses a char array for efficient assignment.

Is Shuffle String asked at Google, Amazon, or Meta?

Shuffle String is an Easy-level array and string manipulation problem commonly used for screening rounds and practice. While not among the most frequently reported problems at top companies, similar index-mapping and permutation problems appear in interviews at companies like Amazon and Google.

Description Hints 2 Solution Video 10:09

1528. Shuffle String

Easy85.5% acceptance2 companies

You are given a string s and an integer array indices of the same length. The string s will be shuffled such that the character at the i^th position moves to indices[i] in the shuffled string.

Return the shuffled string.

Example 1:

Input: s = "codeleet", indices = [4,5,6,7,0,2,1,3]
Output: "leetcode"
Explanation: As shown, "codeleet" becomes "leetcode" after shuffling.

Example 2:

Input: s = "abc", indices = [0,1,2]
Output: "abc"
Explanation: After shuffling, each character remains in its position.

Constraints:

s.length == indices.length == n
1 <= n <= 100
s consists of only lowercase English letters.
0 <= indices[i] < n
All values of indices are unique.

Asked at 2 companies

Microsoft

Google

Topics

Array String

Hints open one at a time

Hint 1

You can create an auxiliary string t of length n.

Hint 2

Assign t[indexes[i]] to s[i] for each i from 0 to n-1.

10:09

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Solution:
2    def restoreString(self, s: str, indices: List[int]) -> str:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

"codeleet"
[4,5,6,7,0,2,1,3]

Input

"abc"
[0,1,2]

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