Skip to content
Related Articles

Related Articles

Improve Article
Save Article
Like Article

Lexicographically smallest string possible by inserting given character

  • Difficulty Level : Medium
  • Last Updated : 21 Apr, 2021

Given a string S and a character C, the task is to place a character in the string in such a way that the string obtained is the lexicographically smallest string.

Examples:

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Input: S = “acd”, C = ‘b’
Output: “abcd”
Explanation: The possible strings formed by placing the character C in string at different indices are [“bacd”, “abcd”, “acbd”, “acdb”]
The lexicographically smallest string obtained is “abcd”.



Input: S = “abcd”, C=’e’
Output: “abcde”
Explanation: The possible strings formed by placing the character C in string at different indices are {“eabcd”, “aebcd”, “abecd”, “abced”, “abcde”}.
The lexicographically smallest string is “abcde”.

Approach: The idea is to place the character just before the first character which is lexicographically greater than the character C in the string. If no character in the string is found to be greater than C, insert the character at the end.

Below is the implementation of the above approach:

C++




// C++ Program to implement the
// above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to obtain lexicographically
// smallest string possible by inserting
// character c in the string s
string SmallestString(string s, char c)
{
 
    // Traverse the string
    for (int i = 0; i < s.size(); i++) {
 
        // If the current character is greater
        // than the given character
        if (s[i] > c) {
 
            // Insert the character before
            // the greater character
            s.insert(i, 1, c);
 
            // Return the string
            return s;
        }
    }
 
    // Append the character at the end
    s += c;
 
    // Return the string
    return s;
}
 
// Driver Code
int main()
{
    string S = "acd";
    char C = 'b';
 
    cout << SmallestString(S, C) << endl;
 
    return 0;
}

Java




// Java program to implement the
// above approach
import java.util.*;
 
class GFG{
 
// Function to obtain lexicographically
// smallest String possible by inserting
// character c in the String s
static String SmallestString(String s, char c)
{
     
    // Traverse the String
    for(int i = 0; i < s.length(); i++)
    {
         
        // If the current character is greater
        // than the given character
        if (s.charAt(i) > c)
        {
             
            // Insert the character before
            // the greater character
            String temp = s;
            s = s.substring(0, i);
            s += c;
            s += temp.substring(i, temp.length());
             
            // Return the String
            return s;
        }
    }
     
    // Append the character at the end
    s += c;
     
    // Return the String
    return s;
}
 
// Driver Code
public static void main(String args[])
{
    String S = "acd";
    char C = 'b';
     
    System.out.println(SmallestString(S, C));
}
}
 
// This code is contributed by ipg2016107

Python3




# Python3 Program to implement
# the above approach
 
# Function to obtain lexicographically
# smallest string possible by inserting
# character c in the string s
def SmallestString(s, c):
 
    i = 0
 
    # Traverse the string
    while(i < len(s)):
 
      # Check if current character is
      # greater than the given character
        if s[i] > c:
 
            # Insert the character before
            # the first greater character
            s = s[:i] + c + s[i:]
 
            # Return the string
            return s
        i = i + 1
 
    # Append the character at the end
    s = s + c
 
    # Return the string
    return s
 
 
S = 'abd'
C = 'c'
 
# Function call
print(SmallestString(S, C))

C#




// C# program to implement the
// above approach
using System;
 
class GFG{
     
// Function to obtain lexicographically
// smallest String possible by inserting
// character c in the String s
static String SmallestString(String s, char c)
{
     
    // Traverse the String
    for(int i = 0; i < s.Length; i++)
    {
         
        // If the current character is greater
        // than the given character
        if (s[i] > c)
        {
             
            // Insert the character before
            // the greater character
            String temp = s;
            s = s.Substring(0, i);
            s += c;
            s += temp.Substring(i, temp.Length - 1);
             
            // Return the String
            return s;
        }
    }
     
    // Append the character at the end
    s += c;
     
    // Return the String
    return s;
}
 
// Driver Code
public static void Main(String []args)
{
    String S = "acd";
    char C = 'b';
     
    Console.WriteLine(SmallestString(S, C));
}
}
 
// This code is contributed by aashish1995

Javascript




<script>
// javascript program to implement
// the above approach
 
// Function to obtain lexicographically
// smallest String possible by inserting
// character c in the String s
function SmallestString(s, c)
{
      
    // Traverse the String
    for(let i = 0; i < s.length; i++)
    {
          
        // If the current character is greater
        // than the given character
        if (s[i] > c)
        {
              
            // Insert the character before
            // the greater character
            let temp = s;
            s = s.substring(0, i);
            s += c;
            s += temp.substring(i, temp.length);
              
            // Return the String
            return s;
        }
    }
      
    // Append the character at the end
    s += c;
      
    // Return the String
    return s;
}
 
// Driver code
     let S = "acd";
    let C = 'b';
    document.write(SmallestString(S, C));
      
     // This code is contributed by splevel62.
</script>
Output: 
abcd

 

Time Complexity: O(len(str))
Auxiliary Space: O(1)




My Personal Notes arrow_drop_up
Recommended Articles
Page :

Start Your Coding Journey Now!