Last Updated: 19 Nov, 2018
Anagram Pairs
Moderate
Asked in companies
You are given two strings 'str1' and 'str1'.
You have to tell whether these strings form an anagram pair or not.
The strings form an anagram pair if the letters of one string can be rearranged to form another string.
Pre-requisites:
Anagrams are defined as words or names that can be formed by rearranging the letters of another word. Such as "spar" can be formed by rearranging letters of "rasp". Hence, "spar" and "rasp" are anagrams.
Other examples include:
'triangle' and 'integral'
'listen' and 'silent'
Note:
Since it is a binary problem, there is no partial marking. Marks will only be awarded if you get all the test cases correct.
Input format:
The first and the only line of input contains two single space-separated strings Str1 and Str2, respectively.
Output format:
The only line of output contains either True or False. True, if the given two strings form an anagram pair and False otherwise.
You don't have to explicitly print by yourself. It has already been taken care of.
Remember/Consider:
Neither of the two input strings contains spaces in between, except to differentiate one from the other.
Also, both the strings will be in lowercase characters.
Approaches
Anagrams have a unique property: the counts of each distinct character present in both strings are the same. One way to check this is:
- Sort both strings, so that all the same characters come together
- Then loop through both strings together and check each element in both strings one by one
- If at any position, the characters are found to be different or if the lengths of the two strings are different, they cannot be anagrams
- Otherwise, they will be anagrams
- Create a 26 sized array. Each element A[i] of the array stores the difference of the frequencies of the (i + 1)th alphabet in the strings.
At i=0, frequency of ‘a’ is stored because it is the first character.
For example, if A[2] is -2, that means:
Frequency of ‘c’ in first string - Frequency of ‘c’ in second string = -2
2. To create this array, first initialize an array of size 26 and fill it with zeros.
3. Iterate through the characters of the first string and increase the element at the corresponding location by 1. For example if the current character is denoted by ‘c’ and the array by arr, then you’ll do arr['c' - ‘a’] += 1. This works because all characters are lowercase.
4. Then repeat the previous step for the second array but this time, decrease the element at the corresponding location by 1
5. Now iterate through the array and see if all elements in it are zero. If any one element is non zero, then the strings are not anagrams. Otherwise, they are anagrams