All substrings of a given String
Last Updated :
14 Feb, 2025
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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"
[Expected Approach] - Using Iteration
- The idea is to use two nested loops.
- The outer loop picks the starting index (loop for i from 0 to n-1)
- The inner loop picks the ending ending index (loop for j to n-1)
// C++ program to find all the
// substrings of given string
#include <bits/stdc++.h>
using namespace std;
// Function to find all substrings
vector<string> 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<string> res = findSubstrings(s);
for(auto i:res) {
cout<< i <<" ";
}
return 0;
}
#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;
}
// Function to find all substrings
import java.util.ArrayList;
import java.util.List;
public class Main {
public static List<String> 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 + " ");
}
}
}
# Function to find all substrings
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
s = 'abc'
res = find_substrings(s)
for i in res:
print(i, end=' ')
// Function to find all substrings
using System;
using System.Collections.Generic;
class Program {
public static List<string> 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 + " ");
}
}
}
// Function to find all substrings
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;
}
let s = 'abc';
let res = findSubstrings(s);
res.forEach(i => {
process.stdout.write(i + ' ');
});
Output
a ab abc b bc c
[Interesting Approach] - Using Recursion
The idea is to recursively generate all possible substrings of the given string s. To do so, create an array of string res[] to store the substrings of string s and an empty string cur to store the current string. Start from the 0th index and for each index ind, add the current character s[ind] in the string cur, and add the string cur in res[]. Then, move to index ind + 1, and recursively generate the all substrings. At each recursive call, check if string cur is empty, if so, skip the current character to start the string from next index ind + 1. At last print all the substrings.
// C++ program to find all the
// substrings of given string
#include <bits/stdc++.h>
using namespace std;
// Recursive Function to find all
// substrings of a string
void subString(string &s, int n, int index,
string &cur, vector<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.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<string> 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<string> res = findSubstrings(s);
for(auto i:res) {
cout<< i <<" ";
}
return 0;
}
// Java program to find all the
// substrings of given string
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 program to find all the
# substrings of given string
# Recursive Function to find all
# substrings of a string
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# program to find all the
// substrings of given string
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 program to find all the
// substrings of given string
// Recursive Function to find all
// substrings of a string
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;
}
const s = "abc";
const res = findSubstrings(s);
console.log(res.join(" "));
Output
a ab abc b bc c
