Different substrings in a string that start and end with given strings

26 Sep, 2021
Given a string s and two other strings begin and end, find the number of different substrings in the string which begin and end with the given begin and end strings.
Examples: 
Input : s = "geeksforgeeks"
        begin = "geeks"
        end = "for"
Output : 1

Input : s = "vishakha"
        begin = "h"
        end = "a"
Output : 2
Two different sub-strings are "ha" and "hakha".
Approach: Find all occurrences of string begin and string end. Store the index of each string in two different arrays. After that traverse through the whole string and add one symbol per iteration to already seen sub-strings and map new strings to some non-negative integers. As the ends and beginnings of strings and different strings of equal length are mapped to different numbers (and equal strings are mapped equally), simply count the number of necessary sub-strings of a certain length. 
C++
Java
Python3
C#
Javascript
// Cpp program to find number of// different sub strings#include <bits/stdc++.h>using namespace std; // function to return number of different// sub-stringsint numberOfDifferentSubstrings(string s, string a,                                          string b){    // initially our answer is zero.    int ans = 0;     // find the length of given strings    int ls = s.size(), la = a.size(), lb = b.size();     // currently make array and initially put zero.    int x[ls] = { 0 }, y[ls] = { 0 };     // find occurrence of "a" and "b" in string "s"    for (int i = 0; i < ls; i++) {        if (s.substr(i, la) == a)            x[i] = 1;        if (s.substr(i, lb) == b)            y[i] = 1;    }     // We use a hash to make sure that same    // substring is not counted twice.    unordered_set<string> hash;        // go through all the positions to find    // occurrence of "a" first.    string curr_substr = "";    for (int i = 0; i < ls; i++) {             // if we found occurrence of "a".        if (x[i]) {                     // then go through all the positions            // to find occurrence of "b".            for (int j = i; j < ls; j++) {                             // if we do found "b" at index                // j then add it to already                // existed substring.                if (!y[j])                    curr_substr += s[j];                 // if we found occurrence of "b".                if (y[j]) {                                     // now add string "b" to                    // already existed substring.                    curr_substr += s.substr(j, lb);                                         // If current substring is not                    // included already.                    if (hash.find(curr_substr) == hash.end())                        ans++;                     // put any non negative                    // integer to make this                    // string as already                    // existed.                    hash.insert(curr_substr);                }            }             // make substring null.            curr_substr = "";        }    }     // return answer.    return ans;} // Driver program for above function.int main(){    string s = "codecppforfood";    string begin = "c";    string end = "d";    cout << numberOfDifferentSubstrings(s, begin, end)        << endl;    return 0;}
// Java program to find number of// different sub stringsimport java.util.HashSet; class GFG{ // function to return number of// different sub-stringsstatic int numberOfDifferentSubstrings(String s,                                       char a, char b){     // initially our answer is zero.    int ans = 0;     // find the length of given strings    int ls = s.length();     // currently make array and    // initially put zero.    int[] x = new int[ls];    int[] y = new int[ls];     // find occurrence of "a" and "b"    // in string "s"    for (int i = 0; i < ls; i++)    {        if (s.charAt(i) == a)            x[i] = 1;        if (s.charAt(i) == b)            y[i] = 1;    }     // We use a hash to make sure that same    // substring is not counted twice.    HashSet<String> hash = new HashSet<>();     // go through all the positions to find    // occurrence of "a" first.    String curr_substr = "";    for (int i = 0; i < ls; i++)    {         // if we found occurrence of "a".        if (x[i] != 0)        {             // then go through all the positions            // to find occurrence of "b".            for (int j = i; j < ls; j++)            {                 // if we do found "b" at index                // j then add it to already                // existed substring.                if (y[j] == 0)                    curr_substr += s.charAt(i);                 // if we found occurrence of "b".                if (y[j] != 0)                {                     // now add string "b" to                    // already existed substring.                    curr_substr += s.charAt(j);                     // If current substring is not                    // included already.                    if (!hash.contains(curr_substr))                        ans++;                     // put any non negative                    // integer to make this                    // string as already                    // existed.                    hash.add(curr_substr);                }            }             // make substring null.            curr_substr = "";        }    }     // return answer.    return ans;} // Driver Codepublic static void main(String[] args){    String s = "codecppforfood";    char begin = 'c';    char end = 'd';    System.out.println(           numberOfDifferentSubstrings(s, begin, end));}} // This code is contributed by// sanjeev2552
# Python 3 program to find number of# different sub strings # function to return number of different# sub-stringsdef numberOfDifferentSubstrings(s, a, b):     # initially our answer is zero.    ans = 0     # find the length of given strings    ls = len(s)    la = len(a)    lb = len(b)     # currently make array and initially    # put zero.    x = [0] * ls    y = [0] * ls     # find occurrence of "a" and "b" in string "s"    for i in range(ls):                 if (s[i: la + i] == a):            x[i] = 1        if (s[i: lb + i] == b):            y[i] = 1     # We use a hash to make sure that same    # substring is not counted twice.    hash = []     # go through all the positions to find    # occurrence of "a" first.    curr_substr = ""    for i in range(ls):             # if we found occurrence of "a".        if (x[i]):                     # then go through all the positions            # to find occurrence of "b".            for j in range( i, ls):                             # if we do found "b" at index                # j then add it to already                # existed substring.                if (not y[j]):                    curr_substr += s[j]                 # if we found occurrence of "b".                if (y[j]):                                     # now add string "b" to                    # already existed substring.                                     curr_substr += s[j: lb + j]                                         # If current substring is not                    # included already.                    if curr_substr not in hash:                        ans += 1                     # put any non negative integer                    # to make this string as already                    # existed.                    hash.append(curr_substr)             # make substring null.            curr_substr = ""     # return answer.    return ans # Driver Codeif __name__ == "__main__":         s = "codecppforfood"    begin = "c"    end = "d"    print(numberOfDifferentSubstrings(s, begin, end)) # This code is contributed by ita_c
// C# program to find number of// different sub stringsusing System;using System.Collections.Generic; class GFG{ // function to return number of// different sub-stringsstatic int numberOfDifferentSubstrings(String s,                                    char a, char b){     // initially our answer is zero.    int ans = 0;     // find the length of given strings    int ls = s.Length;     // currently make array and    // initially put zero.    int[] x = new int[ls];    int[] y = new int[ls];     // find occurrence of "a" and "b"    // in string "s"    for (int i = 0; i < ls; i++)    {        if (s[i] == a)            x[i] = 1;        if (s[i] == b)            y[i] = 1;    }     // We use a hash to make sure that same    // substring is not counted twice.    HashSet<String> hash = new HashSet<String>();     // go through all the positions to find    // occurrence of "a" first.    String curr_substr = "";    for (int i = 0; i < ls; i++)    {         // if we found occurrence of "a".        if (x[i] != 0)        {             // then go through all the positions            // to find occurrence of "b".            for (int j = i; j < ls; j++)            {                 // if we do found "b" at index                // j then add it to already                // existed substring.                if (y[j] == 0)                    curr_substr += s[i];                 // if we found occurrence of "b".                if (y[j] != 0)                {                     // now add string "b" to                    // already existed substring.                    curr_substr += s[j];                     // If current substring is not                    // included already.                    if (!hash.Contains(curr_substr))                        ans++;                     // put any non negative                    // integer to make this                    // string as already                    // existed.                    hash.Add(curr_substr);                }            }             // make substring null.            curr_substr = "";        }    }     // return answer.    return ans;} // Driver Codepublic static void Main(String[] args){    String s = "codecppforfood";    char begin = 'c';    char end = 'd';    Console.WriteLine(        numberOfDifferentSubstrings(s, begin, end));}} // This code is contributed by Rajput-Ji
<script> // Javascript program to find number of// different sub strings     // function to return number of// different sub-stringsfunction numberOfDifferentSubstrings(s,a,b){    // initially our answer is zero.    let ans = 0;       // find the length of given strings    let ls = s.length;       // currently make array and    // initially put zero.    let x = new Array(ls);    let y = new Array(ls);         for(let i=0;i<ls;i++)    {        x[i]=0;        y[i]=0;    }       // find occurrence of "a" and "b"    // in string "s"    for (let i = 0; i < ls; i++)    {        if (s[i] == a)            x[i] = 1;        if (s[i] == b)            y[i] = 1;    }       // We use a hash to make sure that same    // substring is not counted twice.    let hash = new Set();       // go through all the positions to find    // occurrence of "a" first.    let curr_substr = "";    for (let i = 0; i < ls; i++)    {           // if we found occurrence of "a".        if (x[i] != 0)        {               // then go through all the positions            // to find occurrence of "b".            for (let j = i; j < ls; j++)            {                   // if we do found "b" at index                // j then add it to already                // existed substring.                if (y[j] == 0)                    curr_substr += s[i];                   // if we found occurrence of "b".                if (y[j] != 0)                {                       // now add string "b" to                    // already existed substring.                    curr_substr += s[j];                       // If current substring is not                    // included already.                    if (!hash.has(curr_substr))                        ans++;                       // put any non negative                    // integer to make this                    // string as already                    // existed.                    hash.add(curr_substr);                }            }               // make substring null.            curr_substr = "";        }    }       // return answer.    return ans;    }         // Driver Code    let s = "codecppforfood";    let begin = 'c';    let end = 'd';    document.write(numberOfDifferentSubstrings(s, begin, end));         // This code is contributed by rag2127     </script>
Output: 
3
ukasp
sanjeev2552
nidhi_biet
Rajput-Ji
rag2127
saurabh1990aror
gabaa406
Hash
Strings
Hash
Strings
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
What is Hashing | A Complete Tutorial
Find k numbers with most occurrences in the given array
Real-time application of Data Structures
Non-Repeating Element
Find the length of largest subarray with 0 sum
Write a program to reverse an array or string
Reverse a string in Java
Write a program to print all permutations of a given string
C++ Data Types
Different Methods to Reverse a String in C++