Find distinct characters in distinct substrings of a string

Given a string str, the task is to find the count of distinct characters in all the distinct sub-strings of the given string.

Examples:

Input: str = “ABCA”
Output: 18

Distinct sub-strings Distinct characters
A 1
AB 2
ABC 3
ABCA 3
B 1
BC 2
BCA 3
C 1
CA 2

Hence, 1 + 2 + 3 + 3 + 1 + 2 + 3 + 1 + 2 = 18

Input: str = “AAAB”
Output: 10



Approach: Take all possible sub-strings of the given string and use a set to check whether the current sub-string has been processed before. Now, for every distinct sub-string, count the distinct characters in it (again set can be used to do so). The sum of this count for all the distinct sub-strings is the final answer.

Below is the implementation of the above approach:

C++

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// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the count of distinct
// characters in all the distinct
// sub-strings of the given string
int countTotalDistinct(string str)
{
    int cnt = 0;
  
    // To store all the sub-strings
    set<string> items;
  
    for (int i = 0; i < str.length(); ++i) {
  
        // To store the current sub-string
        string temp = "";
  
        // To store the characters of the
        // current sub-string
        set<char> ans;
        for (int j = i; j < str.length(); ++j) {
            temp = temp + str[j];
            ans.insert(str[j]);
  
            // If current sub-string hasn't
            // been stored before
            if (items.find(temp) == items.end()) {
  
                // Insert it into the set
                items.insert(temp);
  
                // Update the count of
                // distinct characters
                cnt += ans.size();
            }
        }
    }
  
    return cnt;
}
  
// Driver code
int main()
{
    string str = "ABCA";
  
    cout << countTotalDistinct(str);
  
    return 0;
}

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Java














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// Java implementation of the approach 


import java.util.HashSet; 


  


class geeks 


{ 


  


    // Function to return the count of distinct 


    // characters in all the distinct 


    // sub-strings of the given string 


    public static int countTotalDistinct(String str)  


    { 


        int cnt = 0; 


  


        // To store all the sub-strings 


        HashSet<String> items = new HashSet<>(); 


  


        for (int i = 0; i < str.length(); ++i)  


        { 


  


            // To store the current sub-string 


            String temp = ""; 


  


            // To store the characters of the 


            // current sub-string 


            HashSet<Character> ans = new HashSet<>(); 


            for (int j = i; j < str.length(); ++j)  


            { 


                temp = temp + str.charAt(j); 


                ans.add(str.charAt(j)); 


  


                // If current sub-string hasn't 


                // been stored before 


                if (!items.contains(temp))  


                { 


  


                    // Insert it into the set 


                    items.add(temp); 


  


                    // Update the count of 


                    // distinct characters 


                    cnt += ans.size(); 


                } 


            } 


        } 


  


        return cnt; 


    } 


  


    // Driver code 


    public static void main(String[] args)  


    { 


        String str = "ABCA"; 


        System.out.println(countTotalDistinct(str)); 


    } 


} 


  


// This code is contributed by 


// sanjeev2552 



















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Python3














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# Python3 implementation of the approach  


  


# Function to return the count of distinct  


# characters in all the distinct  


# sub-strings of the given string  


def countTotalDistinct(string) :  


  


    cnt = 0;  


  


    # To store all the sub-strings  


    items = set();  


  


    for i in range(len(string)) : 


  


        # To store the current sub-string  


        temp = "";  


  


        # To store the characters of the  


        # current sub-string  


        ans = set();  


        for j in range(i, len(string)) : 


            temp = temp + string[j];  


            ans.add(string[j]);  


  


            # If current sub-string hasn't  


            # been stored before  


            if temp not in items : 


  


                # Insert it into the set  


                items.add(temp);  


  


                # Update the count of  


                # distinct characters  


                cnt += len(ans);  


  


    return cnt;  


  


  


# Driver code  


if __name__ == "__main__" :  


  


    string = "ABCA";  


  


    print(countTotalDistinct(string));  


      


# This code is contributed by AnkitRai01 



















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C#














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// C# implementation of the approach 


using System; 


using System.Collections.Generic; 


  


class geeks 


{ 


  


    // Function to return the count of distinct 


    // characters in all the distinct 


    // sub-strings of the given string 


    public static int countTotalDistinct(String str)  


    { 


        int cnt = 0; 


  


        // To store all the sub-strings 


        HashSet<String> items = new HashSet<String>(); 


  


        for (int i = 0; i < str.Length; ++i)  


        { 


  


            // To store the current sub-string 


            String temp = ""; 


  


            // To store the characters of the 


            // current sub-string 


            HashSet<char> ans = new HashSet<char>(); 


            for (int j = i; j < str.Length; ++j)  


            { 


                temp = temp + str[j]; 


                ans.Add(str[j]); 


  


                // If current sub-string hasn't 


                // been stored before 


                if (!items.Contains(temp))  


                { 


  


                    // Insert it into the set 


                    items.Add(temp); 


  


                    // Update the count of 


                    // distinct characters 


                    cnt += ans.Count; 


                } 


            } 


        } 


  


        return cnt; 


    } 


  


    // Driver code 


    public static void Main(String[] args)  


    { 


        String str = "ABCA"; 


        Console.WriteLine(countTotalDistinct(str)); 


    } 


} 


  


// This code is contributed by 29AjayKumar 



















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Output:


18







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