Anagram Check Techniques in DSA Python - Execution Trace

Concept Flow - Anagram Check Techniques

Input two strings s1, s2

↓

Check length equal?

No→Return False

Yes↓

Choose technique

↓

Sort & Compare

↓

Compare results

↓

Return True if match, else False

Start by checking if strings have equal length. Then use one of three techniques: sorting both strings and comparing, counting characters with arrays, or using hash maps to count. Finally, compare results to decide if anagrams.

Execution Sample

DSA Python

def are_anagrams(s1, s2):
    if len(s1) != len(s2):
        return False
    return sorted(s1) == sorted(s2)

This code checks if two strings are anagrams by sorting both and comparing.

Execution Table

Step	Operation	s1	s2	Sorted s1	Sorted s2	Comparison Result	Return Value
1	Input strings	listen	silent	-	-	-	-
2	Check length equal	6	6	-	-	-	Continue
3	Sort s1	-	-	e i l n s t	-	-	-
4	Sort s2	-	-	-	e i l n s t	-	-
5	Compare sorted strings	-	-	e i l n s t	e i l n s t	True	-
6	Return result	-	-	-	-	True	True

💡 Strings have equal length and sorted forms match, so return True

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
s1	listen	listen	listen	listen	listen	listen
s2	silent	silent	silent	silent	silent	silent
sorted_s1	-	-	e i l n s t	e i l n s t	e i l n s t	e i l n s t
sorted_s2	-	-	-	e i l n s t	e i l n s t	e i l n s t
comparison_result	-	-	-	-	True	True
return_value	-	-	-	-	-	True

Key Moments - 3 Insights

Why do we check if the lengths of the two strings are equal first?

Because if lengths differ, they cannot be anagrams. This is shown in Step 2 of the execution_table where unequal lengths would cause immediate return False.

Why do we sort both strings before comparing?

Sorting arranges characters in order, so if both sorted strings match exactly (Step 5), they have the same characters in the same counts, confirming an anagram.

Can we just compare the original strings without sorting?

No, because anagrams have same letters but different order. Sorting normalizes order so comparison is valid, as shown in Steps 3-5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the sorted form of s1 at Step 3?

A e i l n s t

B l i s t e n

C s i l e n t

D t s n l e i

💡 Hint

Check the 'Sorted s1' column at Step 3 in the execution_table

At which step does the function decide to return True?

A Step 2

B Step 5

C Step 6

D Step 4

💡 Hint

Look at the 'Return Value' column in the execution_table

If s1 was 'abc' and s2 was 'ab', what would happen at Step 2?

A Continue to sort and compare

B Return True immediately

C Return False immediately

D Error due to different lengths

💡 Hint

Step 2 checks if lengths are equal; if not, returns False

Concept Snapshot

Anagram Check Techniques:
1. Check if strings have equal length.
2. Sort both strings and compare.
3. Alternatively, count characters using arrays or hash maps.
4. Return True if all characters match, else False.
Sorting method is simple and effective for beginners.

Full Transcript

Anagram check starts by verifying if the two input strings have the same length. If not, they cannot be anagrams and the function returns False immediately. If lengths match, one common technique is to sort both strings alphabetically. After sorting, if the two sorted strings are identical, it means both strings have the same characters in the same quantity, so they are anagrams. The function then returns True. This method is straightforward and easy to implement. Other techniques include counting characters using arrays or hash maps, but sorting is often the simplest to understand and visualize.