What is the time complexity of Split Strings by Separator?

The optimal solution has a time complexity of O(N*M).

What is the space complexity of Split Strings by Separator?

The space complexity is O(N*M).

What data structures are used to solve Split Strings by Separator?

This problem uses Array, String. Understanding these concepts is essential for solving this Easy problem efficiently.

What are the key insights for solving Split Strings by Separator?

Insight 1: The `split()` function (or its equivalent in different languages) is crucial for efficiently separating strings based on a delimiter. Insight 2: Handling empty strings resulting from multiple consecutive separators is important to ensure the correct output. A simple check for non-empty strings after splitting solves this.

Which companies ask LeetCode 2788. Split Strings by Separator in interviews?

This problem is frequently asked at Coupang.

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Split Strings by Separator - LeetCode 2788 Solution

Split Strings by Separator - Complete Solution Guide

Split Strings by Separator is LeetCode problem 2788, a Easy level challenge. This complete guide provides step-by-step explanations, multiple solution approaches, and optimized code in python3, java, cpp, c.

Problem Statement

Given an array of strings words and a character separator , split each string in words by separator . Return an array of strings containing the new strings formed after the splits, excluding empty strings . Notes separator is used to determine where the split should occur, but it is not included as part of the resulting strings. A split may result in more than two strings. The resulting strings must maintain the same order as they were initially given. Example 1: Input: words = ["one.two.three",

Detailed Explanation

The problem asks you to take an array of strings and a separator character as input. For each string in the array, you need to split it into substrings wherever the separator character appears. The output should be a single array containing all the resulting substrings, excluding any empty strings that might arise from consecutive separators. The order of substrings must match the order of the original strings and their substrings.

Solution Approach

The provided solutions use a similar approach. They iterate through each string in the input `words` array. For each string, they split it using the given `separator`. Then, they iterate through the resulting substrings, adding only the non-empty ones to the final result array. This ensures that only meaningful substrings are included in the output.

Step-by-Step Algorithm

Step 1: Initialize an empty result array to store the final substrings.
Step 2: Iterate through each string in the input `words` array.
Step 3: Split each string using the provided `separator` character. This creates an array of substrings.
Step 4: Iterate through the array of substrings obtained in Step 3.
Step 5: Check if each substring is non-empty. If it is, append it to the result array.
Step 6: After processing all strings, return the result array.

Key Insights

Insight 1: The `split()` function (or its equivalent in different languages) is crucial for efficiently separating strings based on a delimiter.
Insight 2: Handling empty strings resulting from multiple consecutive separators is important to ensure the correct output. A simple check for non-empty strings after splitting solves this.
Insight 3: The optimal solution involves iterating through the input strings only once, avoiding redundant operations.

Complexity Analysis

Time Complexity: O(N*M)

Space Complexity: O(N*M)

Topics

This problem involves: Array, String.

Companies

Asked at: Coupang.

Split Strings by Separator | LeetCode 2788

Easy

Array String

Time: O(N*M)Space: O(N*M)

Solution Code

Available in:

import java.util.ArrayList;
import java.util.List;

class Solution {
    public List<String> splitWordsBySeparator(List<String> words, char separator) {
        List<String> result = new ArrayList<>();
        for (String word : words) {
            String[] parts = word.split(String.valueOf(separator).replace("\\", "\\\\"));
            for (String part : parts) {
                if (!part.isEmpty()) {
                    result.add(part);
                }
            }
        }
        return result;
    }
}

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Problem Info

Description

Problem 2788: Split Strings by Separator - Detailed explanation and solution approaches.

Topics

Array String

Companies

Coupang

Stats

Difficulty:Easy

Languages:4

Companies:1

Problem #:2788

Problem Explanation

💡

Think Before You Code

🤔 Ask Yourself

→What is the input? What output do I need?
→Can I solve a smaller version of this problem first?
→What patterns have I seen in similar problems?

✏️ Try This First

Before looking at the solution, try to solve it on paper with a simple example!

🚀 Try on LeetCode

Solution Approach

📋

Step-by-Step Solution

6 steps

1
Step 1: Initialize an empty result array to store the final substrings.
2
Step 2: Iterate through each string in the input `words` array.
3
Step 3: Split each string using the provided `separator` character. This creates an array of substrings.
4
Step 4: Iterate through the array of substrings obtained in Step 3.
5
Step 5: Check if each substring is non-empty. If it is, append it to the result array.
6
Step 6: After processing all strings, return the result array.

💡

Pro Tip for Students

Try tracing through each step with a small example on paper before coding. Understanding "why" each step happens is more important than memorizing the code!

⚡

Complexity Analysis

⏱️

Time Complexity

O(N*M)

💾

Space Complexity

O(N*M)

📝

Why?

The nested loops in the solutions directly contribute to the O(N*M) time complexity. The space used by the result array depends on the number of substrings generated from the splitting process, which can be up to the total number of characters in the input strings.

📖New to Big O? Click to learn more

Big O Notation - Quick Guide

O(1)Best - Instant

O(log n)Excellent - Binary Search

O(n)Good - One loop

O(n log n)OK - Sorting

O(n²)Slow - Nested loops

O(2ⁿ)Very Slow - Recursion

Alternative Approaches

Character-by-Character Iteration

Instead of using the built-in `split()` function, iterate through each character of each string. When a separator is found, add the preceding substring to the result, reset the current substring, and continue.

Time: O(N*M)Space: O(N*M)

Trade-offs: This approach avoids the built-in `split()` function, which might have hidden complexities in certain implementations. However, it increases the code complexity and is generally not preferred for readability and conciseness.

✨

Key Insights

1Insight 1: The `split()` function (or its equivalent in different languages) is crucial for efficiently separating strings based on a delimiter.
2Insight 2: Handling empty strings resulting from multiple consecutive separators is important to ensure the correct output. A simple check for non-empty strings after splitting solves this.
3Insight 3: The optimal solution involves iterating through the input strings only once, avoiding redundant operations.

📚

Key Terms Explained

For Students

Array

A collection of items stored at contiguous memory locations. Like a row of boxes.

String

A sequence of characters. Like a word or sentence in programming!

Edge Cases

Edge case 1: The input array `words` could be empty, resulting in an empty output. The solutions handle this correctly by returning an empty array.
Edge case 2: A string might contain consecutive separators (e.g., "|||"). The solutions correctly handle this by skipping the empty strings generated between these separators.
Edge case 3: The separator might not exist in any of the strings. In this case, each word is added as is to the result list.

⚠️

Common Mistakes to Avoid

✗Common mistake 1: Forgetting to handle empty substrings generated from consecutive separators. This leads to incorrect output.

✗Common mistake 2: Not accounting for the possibility of an empty input array `words` and not handling this edge case correctly.

✗Common mistake 3: In the C solution, improper memory management (forgetting to free allocated memory) could lead to memory leaks.

✅

Learning Tip

Every mistake is a learning opportunity! When you make an error, understand why it happened before moving on.

🌍

Where is This Used in Real Life?

💼Real-world scenario 1: Processing CSV data where fields are separated by commas. This algorithm can be used to parse the data into individual fields.

🏦Real-world scenario 2: Parsing log files where entries are separated by a specific character. This can be useful for extracting specific information from the log files.

🎮Real-world scenario 3: Tokenizing sentences in natural language processing (NLP) where words or phrases are separated by spaces or other punctuation.

💡Understanding real-world applications helps you see the "why" behind algorithms. It's not just about passing interviews—these concepts power the apps and websites you use every day!

Author's Notes

💡 Key Insight

When dealing with arrays, always consider if sorting would simplify the problem. Many array problems have O(n) solutions using hash maps or two-pointer technique.

🎯 Interview Tip

Use this problem to demonstrate clean code practices. Variable naming and code organization matter.

⚠️ Watch Out

Off-by-one errors are the most common mistake. Double-check your loop bounds and array indices.

Written by Saswata Mondal

Software Engineer • Algorithms Enthusiast • Interview Coach

👨‍💻

About the Author

👨‍💻

Saswata MondalAuthor400+ LC Problems

B.Tech CSE, IEM Kolkata | LeetCode Rating: 1672 (Top 15%)

Certified: IBM Java Developer, NPTEL Programming in Java

Last updated: August 28, 2024LeetCode Profile GitHub

This solution has been crafted based on my experience solving 400+ LeetCode problems. Each explanation is designed to help you understand the underlying concepts, not just memorize the code.

Community Tips & Insights

Try solving this without using extra space first. It's a great exercise for understanding the underlying pattern.

@CodeNinjaJul 13

In a real interview, always clarify constraints first. Ask about input size and value ranges.

@TechLeadJul 6

❓

Frequently Asked Questions

What is the most efficient way to solve array problems?

Most array problems can be solved efficiently using techniques like two-pointer approach, sliding window, or hash maps. The key is identifying whether the array is sorted (enabling binary search) or if tracking seen elements (using hash maps) can help achieve O(n) time complexity.

How do I handle string manipulation efficiently?

In languages with immutable strings (Java, Python, C#), use StringBuilder/list to avoid O(n) concatenation cost. Consider using character arrays for in-place modifications. For pattern matching, consider KMP or Rabin-Karp for O(n+m) complexity.

How should I approach easy-level algorithm problems?

Easy problems build foundational skills. Focus on: 1) Understanding the problem completely before coding, 2) Writing clean, readable code, 3) Handling all edge cases (empty input, single element, etc.), 4) Analyzing time and space complexity. Don't skip complexity analysis even for simple solutions.

How should I practice algorithm problems effectively?

Focus on understanding patterns rather than memorizing solutions. After solving a problem, review optimal solutions and understand the intuition. Group similar problems to recognize patterns. Practice explaining your approach out loud. Review problems after a few days to test retention.

What is the optimal approach for "Split Strings by Separator"?

For this easy-level Array problem, the key is to identify the core pattern. Analyze the input constraints to determine acceptable time complexity. Consider whether string techniques can optimize the solution. Always handle edge cases and validate your approach with examples before coding.

🤖 Need help with this problem?