How to use a Map to Count Characters In Javascript
Using a Map, the approach counts characters by iterating over the string. For each character, it updates the count in the Map. Finally, it calculates the count of equal pairs by summing up the counts multiplied by one less than the count.
Example: This function counts the number of equal adjacent pairs in a string by using a Map to track the count of each character.
function countEqualPairs(str) {
let count = 0;
let charCount = new Map();
for (let char of str) {
if (charCount.has(char)) {
count += charCount.get(char);
charCount.set(char, charCount.get(char) + 1);
} else {
charCount.set(char, 1);
}
}
return count;
}
console.log(countEqualPairs("abccba")); // 5
Output
3
JavaScript Program Count number of Equal Pairs in a String
In this article, we are going to learn how can we count a number of equal pairs in a string. Counting equal pairs in a string involves finding and counting pairs of consecutive characters that are the same. This task can be useful in various applications, including pattern recognition and data analysis.
Examples:
Input: 'pqr'
Output: 3
Explanation:
3 pairs that are equal are (p, p), (q, q) and (r, r)
Input: 'HelloWorld'
Output: 18
Table of Content
- Naive Approach
- Efficient appraoch
- Using a Map to Count Characters
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