Given two strings S and T, the task is to merge these two strings by adding one character at a time from the beginning of either string to form a resultant string. The resultant string should be lexicographically the largest string that can be formed by merging the strings S and T.
Examples:
Input: S = “dbcbb”, T = “cdbbb”
Output : dcdbcbbbbbInput : S = “geeks“, T = “forgeeks”
Output : gforgeekseeks
Approach: The simplest idea to solve the problem is to greedily select the first characters from the string which is lexicographically bigger than others. Therefore, Greedy algorithm and Recursion can be used to solve the problem. Follow the steps below to solve the problem:
- If either of the string lengths is 0, then return S + T as the answer.
- If S is lexicographically larger than T, then return S[0] + largestMerge(S.substr(1), T).
- Otherwise, take the first character of T and call the recursive function largestMerge(S, T.substr(1)).
Below is the implementation of the above approach:
// C++ program for the approach #include <bits/stdc++.h> using namespace std;
// Recursive bfunction for finding // the lexicographically largest string string largestMerge(string s1, string s2) { // If either of the string length is 0,
// return the other string
if (s1.size() == 0 || s2.size() == 0)
return s1 + s2;
// If s1 is lexicographically
// larger than s2
if (s1 > s2) {
// Take first character of s1
// and call the function
return s1[0] + largestMerge(s1.substr(1), s2);
}
// Take first character of s2
// and recursively call function for
// remaining string
return s2[0] + largestMerge(s1, s2.substr(1));
} // Driver Code int main()
{ // Given Input
string s1 = "geeks" ;
string s2 = "forgeeks" ;
// Function Call
cout << largestMerge(s1, s2) << endl;
return 0;
} |
// Java program for the approach public class Main
{ // Recursive bfunction for finding
// the lexicographically largest string
static String largestMerge(String s1, String s2)
{
// If either of the string length is 0,
// return the other string
if (s1.length() == 0 || s2.length() == 0 )
return s1 + s2;
// If s1 is lexicographically
// larger than s2
if (s1.compareTo(s2) > 0 ) {
// Take first character of s1
// and call the function
return s1.charAt( 0 )
+ largestMerge(s1.substring( 1 ), s2);
}
// Take first character of s2
// and recursively call function for
// remaining string
return s2.charAt( 0 ) + largestMerge(s1, s2.substring( 1 ));
}
public static void main(String[] args)
{
// Given Input
String s1 = "geeks" ;
String s2 = "forgeeks" ;
// Function Call
System.out.print(largestMerge(s1, s2));
}
} // This code is contributed by divyesh072019. |
# Python program for the above approach # Recursive function for finding # the lexicographically largest string def largestMerge(s1, s2):
# If either of the string length is 0,
# return the other string
if len (s1) = = 0 or len (s2) = = 0 :
return s1 + s2
# If s1 is lexicographically
# larger than s2
if (s1 > s2):
# Take first character of s1
# and call the function
return s1[ 0 ] + largestMerge(s1[ 1 :], s2)
# Take first character of s2
# and recursively call function for
# remaining string
return s2[ 0 ] + largestMerge(s1, s2[ 1 :])
# Driver code if __name__ = = '__main__' :
# Given Input
s1 = "geeks"
s2 = "forgeeks"
# Function call
print (largestMerge(s1, s2))
# This code is contributed by MuskanKalra1 |
// C# program for the approach using System;
class GFG {
// Recursive bfunction for finding
// the lexicographically largest string
static string largestMerge( string s1, string s2)
{
// If either of the string length is 0,
// return the other string
if (s1.Length == 0 || s2.Length == 0)
return s1 + s2;
// If s1 is lexicographically
// larger than s2
if ( string .Compare(s1, s2) == 1) {
// Take first character of s1
// and call the function
return s1[0]
+ largestMerge(s1.Substring(1), s2);
}
// Take first character of s2
// and recursively call function for
// remaining string
return s2[0] + largestMerge(s1, s2.Substring(1));
}
// Driver Code
public static void Main()
{
// Given Input
string s1 = "geeks" ;
string s2 = "forgeeks" ;
// Function Call
Console.Write(largestMerge(s1, s2));
}
} // This code is contributed by ukasp. |
<script> // JavaScript program for the approach
// Recursive bfunction for finding
// the lexicographically largest string
const largestMerge = (s1, s2) =>
{
// If either of the string length is 0,
// return the other string
if (s1.length == 0 || s2.length == 0)
return s1 + s2;
// If s1 is lexicographically
// larger than s2
if (s1 > s2) {
// Take first character of s1
// and call the function
return s1[0] + largestMerge(s1.substr(1), s2);
}
// Take first character of s2
// and recursively call function for
// remaining string
return s2[0] + largestMerge(s1, s2.substr(1));
}
// Driver Code
// Given Input
s1 = "geeks" ;
s2 = "forgeeks" ;
// Function Call
document.write(largestMerge(s1, s2));
// This code is contributed by rakeshsahni
</script> |
gforgeekseeks
Time Complexity: O(M×N), where M and N are the length of string s1 and s2 respectively.
Auxiliary Space: O(1)