# Find the resultant String after replacing X with Y and removing Z

Given a string str, the task is to replace all occurrences of the given X with given Y and also remove any occurrances of the given Z if present in it with no extra space

Examples:

Input: str = “batman”, X = ‘a’, Y = ‘d’, Z = ‘b’
Output: ntdmd

Input: str = “abba”, X = ‘a’, Y = ‘d’, Z = ‘b’
Output: dd

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

• The idea is based on the 2 pointers.
• Let two-variable start and end points to the beginning and end of the string.
• Now if the character at the start is Z, replace it with a character not having Y at another pointer pointing to a location > start keeping in mind to replace character X with Y if found.

Below is the implementation of the above approach:

## C++

 `// C++ program to find the resultant String ` `// after replacing X with Y and removing Z ` ` `  `#include ` `using` `namespace` `std; ` ` `  `// Function to replace and remove ` `void` `replaceRemove(string& s, ``char` `X, ``char` `Y, ``char` `Z) ` `{ ` ` `  `    ``// Two pointer start and end points ` `    ``// to beginning and end position in the string ` `    ``int` `start = 0, end = s.size() - 1; ` ` `  `    ``while` `(start <= end) { ` ` `  `        ``// If start is having Z ` `        ``// find X pos in end and ` `        ``// replace Z with another character ` `        ``if` `(s[start] == Z) { ` ` `  `            ``// Find location for having ` `            ``// different character ` `            ``// insted of Z ` `            ``while` `(end >= 0 && s[end] == Z) { ` `                ``end--; ` `            ``} ` ` `  `            ``// If found swap character ` `            ``// at start and end ` `            ``if` `(end > start) { ` `                ``swap(s[start], s[end]); ` `                ``if` `(s[start] == X) ` `                    ``s[start] = Y; ` `                ``start++; ` `            ``} ` `        ``} ` `        ``// Else increment start ` `        ``// Also checkin for X ` `        ``// at start position ` `        ``else` `{ ` `            ``if` `(s[start] == X) ` `                ``s[start] = Y; ` `            ``start++; ` `        ``} ` `    ``} ` `    ``while` `(s.size() > 0 && s[s.size() - 1] == Z) { ` `        ``s.pop_back(); ` `    ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``string str = ``"batman"``; ` `    ``char` `X = ``'a'``, Y = ``'d'``, Z = ``'b'``; ` ` `  `    ``replaceRemove(str, X, Y, Z); ` ` `  `    ``if` `(str.size() == 0) { ` `        ``cout << -1; ` `    ``} ` `    ``else` `{ ` `        ``cout << str; ` `    ``} ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find the resultant String  ` `// after replacing X with Y and removing Z  ` `class` `GFG ` `{ ` `     `  `    ``// Function to replace and remove  ` `    ``static` `String replaceRemove(``char` `[]s, ``char` `X,  ` `                                   ``char` `Y, ``char` `Z)  ` `    ``{  ` `     `  `        ``// Two pointer start and end points  ` `        ``// to beginning and end position in the string  ` `        ``int` `start = ``0``, end = s.length - ``1``;  ` `     `  `        ``while` `(start <= end) ` `        ``{  ` `     `  `            ``// If start is having Z  ` `            ``// find X pos in end and  ` `            ``// replace Z with another character  ` `            ``if` `(s[start] == Z) ` `            ``{  ` `     `  `                ``// Find location for having  ` `                ``// different character  ` `                ``// insted of Z  ` `                ``while` `(end >= ``0` `&& s[end] == Z)  ` `                ``{  ` `                    ``end--;  ` `                ``}  ` `     `  `                ``char` `temp ; ` `                 `  `                ``// If found swap character  ` `                ``// at start and end  ` `                ``if` `(end > start)  ` `                ``{  ` `                    ``temp = s[start]; ` `                    ``s[start] = s[end]; ` `                    ``s[end] = temp; ` `                     `  `                    ``if` `(s[start] == X)  ` `                        ``s[start] = Y;  ` `                    ``start++;  ` `                ``}  ` `            ``}  ` `             `  `            ``// Else increment start  ` `            ``// Also checkin for X  ` `            ``// at start position  ` `            ``else`  `            ``{  ` `                ``if` `(s[start] == X)  ` `                    ``s[start] = Y;  ` `                ``start++;  ` `            ``}  ` `        ``}  ` `         `  `        ``String new_s = ``new` `String(s); ` `        ``while` `(new_s.length() > ``0` `&&  ` `            ``new_s.charAt(new_s.length() - ``1``) == Z)  ` `        ``{  ` `            ``new_s = new_s.substring(``0``,new_s.length() - ``1``);  ` `        ``}  ` `        ``return` `new_s; ` `    ``}  ` `     `  `    ``// Driver code  ` `    ``public` `static` `void` `main (String[] args)  ` `    ``{  ` `     `  `        ``String str = ``"batman"``;  ` `        ``char` `X = ``'a'``, Y = ``'d'``, Z = ``'b'``;  ` `     `  `        ``str = replaceRemove(str.toCharArray() , X, Y, Z);  ` `     `  `        ``if` `(str.length() == ``0``) ` `        ``{  ` `            ``System.out.println(-``1``);  ` `        ``}  ` `        ``else` `        ``{  ` `            ``System.out.println(str);  ` `        ``}  ` `    ``}  ` `} ` ` `  `// This code is contributed by AnkitRai01 `

## Python3

 `# Python3 program to find the resultant String  ` `# after replacing X with Y and removing Z  ` ` `  `# Function to replace and remove  ` `def` `replaceRemove(s, X, Y, Z) : ` ` `  `    ``s ``=` `list``(s); ` `     `  `    ``# Two pointer start and end points ` `    ``# to beginning and end position in the string ` `    ``start ``=` `0``; ` `    ``end ``=` `len``(s) ``-` `1``; ` `     `  `    ``while` `(start <``=` `end) : ` `         `  `        ``# If start is having Z ` `        ``# find X pos in end and ` `        ``# replace Z with another character ` `        ``if` `(s[start] ``=``=` `Z) : ` `             `  `            ``# Find location for having ` `            ``# different character ` `            ``# insted of Z  ` `            ``while` `(end >``=` `0` `and` `s[end] ``=``=` `Z) : ` `                ``end ``-``=` `1``; ` `                 `  `            ``# If found swap character  ` `            ``# at start and end ` `            ``if` `(end > start) : ` `                ``s[start], s[end] ``=` `s[end], s[start] ` `                ``if` `(s[start] ``=``=` `X): ` `                    ``s[start] ``=` `Y; ` `                     `  `                ``start ``+``=` `1` `                 `  `        ``# Else increment start ` `        ``# Also checkin for X ` `        ``# at start position ` `        ``else` `: ` `            ``if` `(s[start] ``=``=` `X) : ` `                ``s[start] ``=` `Y; ` `                 `  `            ``start ``+``=` `1``; ` `             `  `    ``while` `(``len``(s) > ``0` `and` `s[``len``(s) ``-` `1``] ``=``=` `Z): ` `        ``s.pop(); ` `         `  `    ``return` `"".join(s) ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `"__main__"` `:  ` ` `  `    ``string ``=` `"batman"``;  ` `    ``X ``=` `'a'``; Y ``=` `'d'``; Z ``=` `'b'``;  ` ` `  `    ``string ``=` `replaceRemove(string, X, Y, Z);  ` ` `  `    ``if` `(``len``(string) ``=``=` `0``) : ` `        ``print``(``-``1``);  ` ` `  `    ``else` `: ` `        ``print``(string);  ` ` `  `# This code is contributed by AnkitRai01 `

## C#

 `// C# program to find the resultant String  ` `// after replacing X with Y and removing Z  ` `using` `System; ` ` `  `class` `GFG ` `{ ` `     `  `    ``// Function to replace and remove  ` `    ``static` `String replaceRemove(``char` `[]s, ``char` `X,  ` `                                ``char` `Y, ``char` `Z)  ` `    ``{  ` `     `  `        ``// Two pointer start and end points  ` `        ``// to beginning and end position in the string  ` `        ``int` `start = 0, end = s.Length - 1;  ` `     `  `        ``while` `(start <= end) ` `        ``{  ` `     `  `            ``// If start is having Z  ` `            ``// find X pos in end and  ` `            ``// replace Z with another character  ` `            ``if` `(s[start] == Z) ` `            ``{  ` `     `  `                ``// Find location for having  ` `                ``// different character  ` `                ``// insted of Z  ` `                ``while` `(end >= 0 && s[end] == Z)  ` `                ``{  ` `                    ``end--;  ` `                ``}  ` `     `  `                ``char` `temp ; ` `                 `  `                ``// If found swap character  ` `                ``// at start and end  ` `                ``if` `(end > start)  ` `                ``{  ` `                    ``temp = s[start]; ` `                    ``s[start] = s[end]; ` `                    ``s[end] = temp; ` `                     `  `                    ``if` `(s[start] == X)  ` `                        ``s[start] = Y;  ` `                    ``start++;  ` `                ``}  ` `            ``}  ` `             `  `            ``// Else increment start  ` `            ``// Also checkin for X  ` `            ``// at start position  ` `            ``else` `            ``{  ` `                ``if` `(s[start] == X)  ` `                    ``s[start] = Y;  ` `                ``start++;  ` `            ``}  ` `        ``}  ` `         `  `        ``String new_s = ``new` `String(s); ` `        ``while` `(new_s.Length > 0 &&  ` `               ``new_s[new_s.Length - 1] == Z)  ` `        ``{  ` `            ``new_s = new_s.Substring(0,new_s.Length - 1);  ` `        ``}  ` `        ``return` `new_s; ` `    ``}  ` `     `  `    ``// Driver code  ` `    ``public` `static` `void` `Main(String[] args)  ` `    ``{  ` `     `  `        ``String str = ``"batman"``;  ` `        ``char` `X = ``'a'``, Y = ``'d'``, Z = ``'b'``;  ` `     `  `        ``str = replaceRemove(str.ToCharArray() , X, Y, Z);  ` `     `  `        ``if` `(str.Length == 0) ` `        ``{  ` `            ``Console.WriteLine(-1);  ` `        ``}  ` `        ``else` `        ``{  ` `            ``Console.WriteLine(str);  ` `        ``}  ` `    ``}  ` `} ` ` `  `// This code is contributed by PrinciRaj1992 `

Output :

`ndtmd`

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Improved By : AnkitRai01, princiraj1992