Count distinct Strings made by removing three consecutive characters

Given a string S of length N(N > 3), the task is to count distinct strings that can be made by removing three consecutive characters from the original string.

Examples: 

Input: S = “aaabcc”
Output: 4 
Explanation: “bcc”, “acc”, “aac”, “aaa”

Input: S = “aaaaa”
Output: 1 
Explanation: “aaa”

Approach: This can be solved with the following idea:

We have to iterate the string. Then we can concatenate the substrings except for three characters from each iterator and store them in a set for removing duplicity. By this, we can get the number of different strings.

Below are the steps involved in the implementation of the code:

• Iterate through the string.
• Maintain a variable for the size of the substring to be removed.
• Concat the leftover string and insert it into the set.
• Return the size of the set at the end.

Below is the implementation of the code :

C++

// C++ Implementation of code
#include <iostream>
#include <set>
using namespace std;

// Function to count distinct strings
// formed
void removeTrio(string s)
{

    // Initialized the set
    set<string> st;

    int n = s.size();

    for (int i = 0; i < n - 2; i++) {

        // Left substring except the trio
        // from i
        string left = s.substr(0, i);

        // Right substring except the
        // trio from i
        string right = s.substr(i + 3, n - i - 3);

        // New substring after concatining
        // the left and the right substring.
        string new_string = left + right;

        // Inserting in the set
        st.insert(new_string);
    }

    // Return the size of set
    cout << st.size() << endl;

    return;
}

// Driver code
int main()
{

    string s = "aaaccc";

    // Function call
    removeTrio(s);
    return 0;
}

Python3

# Python implementation of code
from typing import Set

# Function to count distinct strings formed
def removeTrio(s: str) -> None:

    # Initialized the set
    st: Set[str] = set()

    n: int = len(s)

    for i in range(n - 2):

        # Left substring except the trio from i
        left: str = s[:i]

        # Right substring except the trio from i
        right: str = s[i+3:]

        # New substring after concatining the left and the right substring.
        new_string: str = left + right

        # Inserting in the set
        st.add(new_string)

    # Return the size of set
    print(len(st))

    return

# Driver code
if __name__ == "__main__":

    s: str = "aaaccc"

    # Function call
    removeTrio(s)

# This code is contributed by Susobhan Akhuli

Java

// Java code implementation:

import java.io.*;
import java.util.*;

class GFG {

    // Function to count distinct strings formed
    static void removeTrio(String s)
    {

        // Initialized the set
        HashSet<String> st = new HashSet<>();

        int n = s.length();

        for (int i = 0; i < n - 2; i++) {

            // Left substring except the trio from i
            String left = s.substring(0, i);

            // Right substring except the trio from i
            String right = s.substring(i + 3, n);

            // New substring after concatenating the left
            // and the right substring.
            String new_string = left + right;

            // Inserting in the set
            st.add(new_string);
        }

        // Return the size of set
        System.out.println(st.size());
        return;
    }

    public static void main(String[] args)
    {
        String s = "aaaccc";

        // Function call
        removeTrio(s);
    }
}

// This code is contributed by karthik.

Output

4

Time Complexity : O(N)
Auxiliary Space: O(N*M)