Sorted Permutation Rank InterviewBit Solution

Problem: Sorted Permutation Rank

Problem Description:

Given a string, find the rank of the string amongst its permutations sorted lexicographically. Assume that no characters are repeated.

Example :

Input : 'acb' 
Output : 2  

The order permutations with letters 'a', 'c', and 'b' :  
    abc 
    acb 
    bac 
    bca 
    cab 
    cba 

The answer might not fit in an integer, so return your answer % 1000003.

Approach

Refer the problem Sorted Permutation Rank with Repeats. The approach & solution to the problem is exactly the same, except that we are not considering the frequency of character because, in this problem, characters are unique without repeat.

Time & Space Complexity

Time Complexity: O(N^2)

- For every index we are traversing the string, to find the number of character lesser than the current one.

Space Complexity: O(1)

- Apart from the space taken by our input array, we have taken the constant amount of space, independent of the size of the string.

Solution:

Code in C++