We are given a string having only lowercase alphabets. The task is to find out total number of distinct permutation can be generated by that string.
Input : aab Output : 3 Different permutations are "aab", "aba" and "baa". Input : ybghjhbuytb Output : 1663200
A simple solution is to find all the distinct permutation and count them.
We can find the count without finding all permutation. Idea is to find all the characters that is getting repeated, i.e., frequency of all the character. Then, we divide the factorial of the length of string by multiplication of factorial of frequency of characters.
In second example, number of character is 11 and here h and y are repeated 2 times whereas g is repeated 3 times.
So, number of permutation is 11! / (2!2!3!) = 1663200
Below is the implementation of above idea.
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Improved By : parashar