How to resolve the algorithm Selectively replace multiple instances of a character within a string step by step in the Java programming language
How to resolve the algorithm Selectively replace multiple instances of a character within a string step by step in the Java programming language
Table of Contents
Problem Statement
This is admittedly a trivial task but I thought it would be interesting to see how succinctly (or otherwise) different languages can handle it. Given the string: "abracadabra", replace programatically:
Note that there is no replacement for the third 'a', second 'b' or first 'r'. The answer should, of course, be : "AErBcadCbFD".
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Selectively replace multiple instances of a character within a string step by step in the Java programming language
Problem: The goal of the code is to selectively replace specific characters in a string based on their position and the provided replacement characters.
Implementation:
1. findNth Method:
- This method takes three parameters: a string
s
, a characterc
, and an integern
. - It returns the index of the nth occurrence of character
c
in strings
. - It recursively calls itself, reducing
n
by 1 and using the previous result as the starting index for the next search.
2. selectiveReplace Method:
- This method takes two parameters: a string
s
and an array ofSet
objects (ops
). - It converts the string
s
into a character arraychars
. - It iterates through each
Set
object in theops
array. - For each
Set
, it uses thefindNth
method to find the index of the nth occurrence of theold
character in the strings
. - It then replaces the character at that index with the
rep
character from theSet
. - Finally, it returns a new string created from the modified
chars
array.
Usage:
The code demonstrates the usage of the selectiveReplace
method by applying it to the string "abracadabra" with the following replacement operations:
- Replace the first occurrence of 'a' with 'A'.
- Replace the second occurrence of 'a' with 'B'.
- Replace the fourth occurrence of 'a' with 'C'.
- Replace the fifth occurrence of 'a' with 'D'.
- Replace the first occurrence of 'b' with 'E'.
- Replace the second occurrence of 'r' with 'F'.
Output: The output of the code would be the following string: "ABraCADaEFa".
Source code in the java programming language
int findNth(String s, char c, int n) {
if (n == 1) return s.indexOf(c);
return s.indexOf(c, findNth(s, c, n - 1) + 1);
}
String selectiveReplace(String s, Set... ops) {
char[] chars = s.toCharArray();
for (Set set : ops)
chars[findNth(s, set.old, set.n)] = set.rep;
return new String(chars);
}
record Set(int n, char old, char rep) { }
selectiveReplace("abracadabra",
new Set(1, 'a', 'A'),
new Set(2, 'a', 'B'),
new Set(4, 'a', 'C'),
new Set(5, 'a', 'D'),
new Set(1, 'b', 'E'),
new Set(2, 'r', 'F'));
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