﻿ Java - Find lexicographic rank of a given string

# Java: Find lexicographic rank of a given string

## Java String: Exercise-50 with Solution

Write a Java program to find the lexicographic rank of a given string.

Visual Presentation: Sample Solution:

Java Code:

``````// Importing necessary Java utilities.
import java.util.*;

// Define a class named Main.
class Main {

// Method to calculate factorial of a number recursively.
public static int makefactorial(int n) {
// If n is less than or equal to 2, return n. Otherwise, calculate n * factorial of (n - 1).
return (n <= 2) ? n : n * makefactorial(n - 1);
}

// Method to calculate the lexicographic rank of a given string.
public static int calcuLexicoRank(String str, int n) {
// Counter for the rank initialized to 1.
int ctrOfRank = 1;

// Loop through each character in the string.
for (int i = 0; i < n; i++) {
int ctr = 0;

// Compare the character at index i with subsequent characters.
for (int j = i + 1; j <= n; j++) {
// If the character at index i is greater than the character at index j, increment the counter.
if (str.charAt(i) > str.charAt(j))
ctr++;
}

// Calculate the lexicographic rank using the formula.
ctrOfRank += ctr * makefactorial(n - i);
}
return ctrOfRank; // Return the calculated rank.
}

// Main method to execute the program.
public static void main(String[] args) {
String str = "BDCA";
System.out.println("The Given String is: " + str);
int n = str.length(); // Get the length of the string.
// Display the lexicographic rank of the given string.
System.out.print("The Lexicographic rank of the given string is: " + calcuLexicoRank(str, n - 1));
}
}
```
```

Sample Output:

```The Given String is: BDCA
The Lexicographic rank of the given string is: 12
```

N.B.: Total possible permutations of BDCA are(lexicographic order) :
1   2   3   4   5   6   7   8   9   10   11   12
The BDCA appear in 12 position of permutation (lexicographic order).

Flowchart: Java Code Editor:

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