#include <bits/stdc++.h>
using namespace std;
 
// Recursive function to calculate factorial of a number
int factorial(int n)
{
	return (n <= 2) ? n : n * factorial(n - 1);
}
 
// Function to find Lexicographic rank of a string using 
// std::prev_permutation
int findLexicographicRank(string key)
{
	string str = key;
 
	// sort the string in descending order
	sort(str.rbegin(), str.rend());
 
	int rank = factorial(str.length());		// maximum rank is n!
 
	while(1)
	{
		// if current permutation is equal to the key, return its rank
	 	if (key == str)
	 		return rank;
 
		// find next lexicographically ordered permutation
	 	if (!prev_permutation(str.begin(), str.end()))
	 		break;
 
	 	rank--;
	}
}
 
int main()
{
	string key = "DCBA";
 
	cout << "Lexicographic Rank of " << key << " is " 
			<< findLexicographicRank(key);
 
	return 0;
}
 

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