Leetcode #2796: Repeat String
In this guide, we solve Leetcode #2796 Repeat String 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
Write code that enhances all strings such that you can call the string.replicate(x) method on any string and it will return repeated string x times. Try to implement it without using the built-in method string.repeat.
Quick Facts
- Difficulty: Easy
- Premium: Yes
- Tags: JavaScript
Intuition
We can repeat the string by building the output piece by piece.
Collecting the pieces in a list and joining once avoids quadratic concatenation costs.
Approach
Append the original string to a list times times, then join the list into the final string.
Steps:
- Create an empty list.
- Append
sto ittimestimes. - Join and return the result.
Example
Input: str = "hello", times = 2
Output: "hellohello"
Explanation: "hello" is repeated 2 times
Python Solution
class Solution:
def replicate(self, s: str, times: int) -> str:
if times <= 0:
return ""
parts = []
for _ in range(times):
parts.append(s)
return "".join(parts)
Complexity
The time complexity is where is the output length, and 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.