Anagram Check Techniques in DSA Rust - Build from Scratch

Anagram Check Techniques

📖 Scenario: You are helping a librarian organize books by checking if two book titles are anagrams. Anagrams are words or phrases made by rearranging the letters of another, ignoring spaces and case.

🎯 Goal: Build a Rust program that checks if two given strings are anagrams using a simple technique.

📋 What You'll Learn

Create two string variables with exact values

Add a helper variable to prepare strings for comparison

Write core logic to check if the two strings are anagrams

Print the result as true or false

💡 Why This Matters

🌍 Real World

Checking anagrams helps in organizing and searching text data, such as book titles or names, by grouping similar words.

💼 Career

Understanding string manipulation and comparison is essential for software development roles involving text processing, data cleaning, and search algorithms.

1

Create two string variables

Create two string variables called first and second with these exact values: "Listen" and "Silent"

DSA Rust

# Your code here

Hint

Use String::from to create string variables.

2

Prepare strings for comparison

Add two new variables called first_chars and second_chars that store the lowercase sorted characters of first and second respectively, ignoring spaces

DSA Rust

fn main() {
    let first = String::from("Listen");
    let second = String::from("Silent");
    // Your code here
}

Hint

Use to_lowercase(), chars(), filter(), and sort_unstable() to prepare the strings.

3

Check if strings are anagrams

Create a boolean variable called are_anagrams that is true if first_chars equals second_chars, otherwise false

DSA Rust

fn main() {
    let first = String::from("Listen");
    let second = String::from("Silent");
    let mut first_chars: Vec = first.to_lowercase().chars().filter(|c| !c.is_whitespace()).collect();
    let mut second_chars: Vec = second.to_lowercase().chars().filter(|c| !c.is_whitespace()).collect();
    first_chars.sort_unstable();
    second_chars.sort_unstable();
    // Create are_anagrams variable
}

Hint

Use the equality operator == to compare the sorted character vectors.

4

Print the result

Print the value of are_anagrams using println!

DSA Rust

fn main() {
    let first = String::from("Listen");
    let second = String::from("Silent");
    let mut first_chars: Vec = first.to_lowercase().chars().filter(|c| !c.is_whitespace()).collect();
    let mut second_chars: Vec = second.to_lowercase().chars().filter(|c| !c.is_whitespace()).collect();
    first_chars.sort_unstable();
    second_chars.sort_unstable();
    let are_anagrams = first_chars == second_chars;
    // Print the result
}

Hint

Use println!("{}", are_anagrams); to print the boolean result.

Practice

1. What is the main idea behind checking if two strings are anagrams?

easy

A. Both strings have the same characters with the same frequency

B. Both strings have the same length only

C. Both strings start with the same character

D. Both strings contain only alphabets

Solution

1. Step 1: Understand anagram definition

   Anagrams are words or phrases made by rearranging letters of another, so character frequency must match.

2. Step 2: Compare character frequencies

   Checking if both strings have the same characters with the same counts confirms they are anagrams.

3. Final Answer:

   Both strings have the same characters with the same frequency -> Option A

4. Quick Check:

   Anagram check = same characters & frequency [OK]

Hint: Check if character counts match in both strings [OK]

Common Mistakes:

• Only comparing string lengths
• Ignoring character frequency
• Checking only first characters

2. Which Rust code snippet correctly sorts the characters of a string s to help check anagrams?

easy

A. let mut chars: Vec<char> = s.chars().collect(); chars.sort();

B. let chars = s.sort();

C. let chars = s.chars().sorted();

D. let chars = s.to_vec().sort();

Solution

1. Step 1: Collect characters into a vector

   Use s.chars().collect() to get a vector of characters from the string.

2. Step 2: Sort the vector in place

   Call chars.sort() to sort characters alphabetically for comparison.

3. Final Answer:

   let mut chars: Vec<char> = s.chars().collect(); chars.sort(); -> Option A

4. Quick Check:

   Collect chars then sort vector [OK]

Hint: Collect chars into Vec then call sort() [OK]

Common Mistakes:

• Trying to sort string directly
• Using non-existent sorted() method
• Calling sort() on &str instead of Vec<char>

3. What is the output of this Rust code snippet?

fn main() {
    let s1 = "listen";
    let s2 = "silent";
    let mut v1: Vec<char> = s1.chars().collect();
    let mut v2: Vec<char> = s2.chars().collect();
    v1.sort();
    v2.sort();
    println!("{}", v1 == v2);
}

medium

A. Runtime panic

B. true

C. Compilation error

D. false

Solution

1. Step 1: Convert strings to char vectors and sort

   Both "listen" and "silent" are converted to vectors and sorted alphabetically.

2. Step 2: Compare sorted vectors

   Sorted vectors for both strings become ['e', 'i', 'l', 'n', 's', 't'], so they are equal.

3. Final Answer:

   true -> Option B

4. Quick Check:

   Sorted chars equal means anagrams [OK]

Hint: Sort both strings and compare vectors [OK]

Common Mistakes:

• Expecting false because strings differ
• Confusing sorting with original order
• Thinking println! prints vectors directly

4. Identify the bug in this Rust function that checks if two strings are anagrams:

fn are_anagrams(s1: &str, s2: &str) -> bool {
    let mut v1: Vec<char> = s1.chars().collect();
    let mut v2: Vec<char> = s2.chars().collect();
    v1.sort();
    v2.sort();
    v1 == v2
}

fn main() {
    println!("{}", are_anagrams("abc", "cba"));
}

medium

A. Using == operator on vectors causes error

B. Missing mutable keyword for vectors

C. Should compare lengths before sorting

D. No bug, function works correctly

Solution

1. Step 1: Review vector creation and sorting

   Vectors are mutable and sorted correctly using v1.sort() and v2.sort().

2. Step 2: Check comparison and usage

   Comparing vectors with == is valid and returns true if sorted characters match.

3. Final Answer:

   No bug, function works correctly -> Option D

4. Quick Check:

   Sorting and comparing vectors works fine [OK]

Hint: Sorting vectors and comparing is valid in Rust [OK]

Common Mistakes:

• Thinking == can't compare vectors
• Assuming length check is mandatory
• Forgetting mut keyword (but it's present here)

5. You want to check if two strings are anagrams ignoring case and spaces. Which Rust approach is best?

hard

A. Sort strings without changing case or removing spaces

B. Compare strings directly after trimming spaces only

C. Convert both strings to lowercase, remove spaces, then sort and compare characters

D. Check if lengths match after removing spaces only

Solution

1. Step 1: Normalize strings by lowering case and removing spaces

   Convert both strings to lowercase and remove all spaces to ignore case and whitespace differences.

2. Step 2: Sort characters and compare

   Sort the cleaned character vectors and compare them to confirm anagram status.

3. Final Answer:

   Convert both strings to lowercase, remove spaces, then sort and compare characters -> Option C

4. Quick Check:

   Normalize case and spaces before sorting [OK]

Hint: Lowercase and remove spaces before sorting [OK]

Common Mistakes:

• Ignoring case differences
• Not removing spaces
• Comparing raw strings directly