Without using Extra Data Structure
In this approach, we are using bit manipulation to find the check for repeated characters in a string. we use a bit vector (checker) to efficiently find and collect duplicate characters in a string. It iterates through the string, tracking character occurrences with bitwise operations and stores duplicates in an array
Syntax:
if ((checker & (1 << bitAtIndex)) > 0) {
if (!duplicates.includes(str[i])) {
duplicates.push(str[i]);
}
} else {
checker |= (1 << bitAtIndex);
};
Example: In this example we are using above-explained apporach.
function findDuplicateChar(str) {
let checker = 0;
const duplicates = [];
for (let i = 0; i < str.length; i++) {
const bitAtIndex =
str.charCodeAt(i) - 'a'.charCodeAt(0);
if ((checker & (1 << bitAtIndex)) > 0) {
if (!duplicates.includes(str[i])) {
duplicates.push(str[i]);
}
} else {
checker |= (1 << bitAtIndex);
}
}
return duplicates;
}
const str = "w3wiki";
const duplicateCharacters = findDuplicateChar(str);
if (duplicateCharacters.length > 0) {
console.log(
"The String ${str} has duplicate characters:",
duplicateCharacters.join(", "));
} else {
console.log(
`The String ${str} has all unique characters`);
};
Output
The String ${str} has duplicate characters: e, G, k, s
JavaScript Program to Check for Repeated Characters in a String
In this article, we are going to see various methods with which you can detect repeated characters in a string. Checking for repeated characters in a string involves examining the string’s content to identify if any character occurs more than once. This helps detect duplications or repetitions within the text.
Input: Str = “w3wiki”
Output:
e, count = 4
g, count = 2
k, count = 2
s, count = 2
Explanation: e,g,k,and s are characters which are occured in string in more than one times.
There are several methods that can be used to Check for repeated characters in a string JavaScript.
Table of Content
- Using sort() method with for…of loop
- Using a Set in JavaScript
- Without using Extra Data Structure
- Using a Map
- Using Object as a Frequency Counter:
We will explore all the above methods along with their basic implementation with the help of examples.