All substrings of a given String (original) (raw)

Last Updated : 13 Feb, 2026

Given a string s, containing lowercase alphabetical characters. The task is to print all non-empty substrings of the given string.

**Examples :

**Input : s = "abc"
**Output : "a", "ab", "abc", "b", "bc", "c"

**Input : s = "ab"
**Output : "a", "ab", "b"

**Input : s = "a"
**Output : "a"

Table of Content

• [Approach 1] Using Iteration - O(n^3) Time and O(n^3) Space
• [Approach 2] Using Recursion - O(n^3) Time and O(n^3) Space

[Approach 1] Using Iteration - O(n^3) Time and O(n^3) Space

The idea is to use two nested loops. The outer loop selects the starting index from 0 to n-1, and for each starting index, the inner loop selects the ending index from that position up to n-1.

C++ `

#include using namespace std;

// Function to find all substrings vector findSubstrings(string &s) {

// to store all substrings
vector<string> res;

for(int i = 0; i < s.length(); i++) {
    for(int j = i; j < s.length(); j++) {
        
        // substr function takes starting index
        // and length as parameters
        res.push_back(s.substr(i, j-i+1));
    }
}

return res;

}

int main() { string s = "abc"; vector res = findSubstrings(s); for(auto i:res) { cout<< i <<" "; } return 0; }

C

#include <stdio.h> #include <string.h>

// Function to find all substrings void findSubstrings(char *s) {

// to store all substrings
int len = strlen(s);
for (int i = 0; i < len; i++) {
    for (int j = i; j < len; j++) {
        for (int k = i; k <= j; k++) {
            putchar(s[k]);
        }
        printf(" ");
    }
}

}

int main() { char s[] = "abc"; findSubstrings(s); return 0; }

Java

import java.util.ArrayList; import java.util.List;

public class GFG { public static List findSubstrings(String s) {

    // to store all substrings
    List<String> res = new ArrayList<>();
    for (int i = 0; i < s.length(); i++) {
        for (int j = i; j < s.length(); j++) {
            
            // substr function takes starting index
            // and ending index + 1 as parameters
            res.add(s.substring(i, j + 1));
        }
    }
    return res;
}

public static void main(String[] args) {
    String s = "abc";
    List<String> res = findSubstrings(s);
    for (String i : res) {
        System.out.print(i + " ");
    }
}

}

Python

def find_substrings(s):

# to store all substrings
res = []
for i in range(len(s)):
    for j in range(i, len(s)):
        res.append(s[i:j+1])
return res

def main(): s = 'abc' res = find_substrings(s) for i in res: print(i, end=' ')

if name == "main": main()

C#

using System; using System.Collections.Generic;

class GFG { public static List FindSubstrings(string s) {

    List<string> res = new List<string>();
    
    for (int i = 0; i < s.Length; i++) {
        for (int j = i; j < s.Length; j++) {
            
            // substr function takes starting index
            // and length as parameters
            res.Add(s.Substring(i, j - i + 1));
        }
    }
    return res;
}

static void Main() {
    string s = "abc";
    List<string> res = FindSubstrings(s);
    foreach (var i in res) {
        Console.Write(i + " ");
    }
}

}

JavaScript

function findSubstrings(s) {

// to store all substrings
let res = [];
for (let i = 0; i < s.length; i++) {
    for (let j = i; j < s.length; j++) {
        
        // substr function takes starting index
        // and ending index + 1 as parameters
        res.push(s.substring(i, j + 1));
    }
}
return res;

}

//Driver Code let s = 'abc'; let res = findSubstrings(s); res.forEach(i => { console.log(i + ' '); });

`

[Approach 2] Using Recursion - O(n^3) Time and O(n^3) Space

The idea is to use recursion to generate all substrings. Start from index 0 and build a current string cur by adding one character at a time. After adding each character, store cur in the result list. Then recursively move to the next index to continue building longer substrings. If cur becomes empty, skip the current character and start forming substrings from the next index.

C++ `

#include using namespace std;

// Recursive Function to find all // substrings of a string void subString(string &s, int n, int index, string &cur, vector &res) {

// if we have reached the 
// end of the string
if (index == n) {
    return;
}

// add the character s[index] 
// to the current string
cur.push_back(s[index]);

// add the current string in result
res.push_back(cur);

// move to next index
subString(s, n, index + 1, cur, res);

// remove the current character
// from the current string 
cur.pop_back();


// if current string is empty
// skip the current index to
// start the new substring
if(cur.empty()) {
    subString(s, n, index + 1, cur, res);
}

}

// Function to find all substrings vector findSubstrings(string s) {

// to store all substrings
vector<string> res;

// to store current string
string cur = "";
subString(s, s.length(), 0, cur, res);
return res;

}

int main() { string s = "abc"; vector res = findSubstrings(s); for(auto i:res) { cout<< i <<" "; } return 0; }

Java

import java.util.*;

class GFG {

// Recursive Function to find all
// substrings of a string
static void subString(String s, int n, int index,
                      StringBuilder cur, List<String> res) {

    // if we have reached the
    // end of the string
    if (index == n) {
        return;
    }

    // add the character s.charAt(index)
    // to the current string
    cur.append(s.charAt(index));

    // add the current string in result
    res.add(cur.toString());

    // move to next index
    subString(s, n, index + 1, cur, res);

    // remove the current character
    // from the current string
    cur.deleteCharAt(cur.length() - 1);

    // if current string is empty
    // skip the current index to
    // start the new substring
    if (cur.length() == 0) {
        subString(s, n, index + 1, cur, res);
    }
}

// Function to find all substrings
static List<String> findSubstrings(String s) {

    // to store all substrings
    List<String> res = new ArrayList<>();

    // to store current string
    StringBuilder cur = new StringBuilder();
    subString(s, s.length(), 0, cur, res);
    return res;
}

public static void main(String[] args) {
    String s = "abc";
    List<String> res = findSubstrings(s);
    for (String str : res) {
        System.out.print(str + " ");
    }
}

}

Python

def subString(s, n, index, cur, res):

# if we have reached the
# end of the string
if index == n:
    return

# add the character s[index]
# to the current string
cur += s[index]

# add the current string in result
res.append(cur)

# move to next index
subString(s, n, index + 1, cur, res)

# remove the current character
# from the current string
cur = cur[:-1]

# if current string is empty
# skip the current index to
# start the new substring
if not cur:
    subString(s, n, index + 1, cur, res)

Function to find all substrings

def findSubstrings(s):

# to store all substrings
res = []

# to store current string
cur = ""
subString(s, len(s), 0, cur, res)
return res

if name == "main": s = "abc" res = findSubstrings(s) print(" ".join(res))

C#

using System; using System.Collections.Generic;

class GFG {

// Recursive Function to find all
// substrings of a string
static void subString(string s, int n, int index,
                      List<char> cur, List<string> res) {

    // if we have reached the
    // end of the string
    if (index == n) {
        return;
    }

    // add the character s[index]
    // to the current string
    cur.Add(s[index]);

    // add the current string in result
    res.Add(new string(cur.ToArray()));

    // move to next index
    subString(s, n, index + 1, cur, res);

    // remove the current character
    // from the current string
    cur.RemoveAt(cur.Count - 1);

    // if current string is empty
    // skip the current index to
    // start the new substring
    if (cur.Count == 0) {
        subString(s, n, index + 1, cur, res);
    }
}

// Function to find all substrings
static List<string> findSubstrings(string s) {

    // to store all substrings
    List<string> res = new List<string>();

    // to store current string
    List<char> cur = new List<char>();
    subString(s, s.Length, 0, cur, res);
    return res;
}

public static void Main() {
    string s = "abc";
    List<string> res = findSubstrings(s);
    Console.WriteLine(string.Join(" ", res));
}

}

JavaScript

function subString(s, n, index, cur, res) {

// if we have reached the
// end of the string
if (index === n) {
    return;
}

// add the character s[index]
// to the current string
cur += s[index];

// add the current string in result
res.push(cur);

// move to next index
subString(s, n, index + 1, cur, res);

// remove the current character
// from the current string
cur = cur.slice(0, -1);

// if current string is empty
// skip the current index to
// start the new substring
if (cur.length === 0) {
    subString(s, n, index + 1, cur, res);
}

}

// Function to find all substrings function findSubstrings(s) {

// to store all substrings
let res = [];

// to store current string
let cur = "";
subString(s, s.length, 0, cur, res);
return res;

}

//Driver Code const s = "abc"; const res = findSubstrings(s); console.log(res.join(" "));

`