How to usea Set in Javascript
Here we will use a set to keep track of the elements you have seen so far. When we encounter a repeating element, check if it exists in the set. If it does, compare its index with the current minimum index.
Syntax:
const seen = new Set();
function findMinIndexWithSet(arr) {
// Using a Map to store the indices of elements
const seen = new Map();
let minIndex = -1;
for (let i = 0; i < arr.length; i++) {
if (seen.has(arr[i])) {
// Check if we found a repeating element
const firstIndex = seen.get(arr[i]);
if (minIndex === -1 || firstIndex < minIndex) {
// If it's the first repeating element or
//it's closer to the beginning of the array
minIndex = firstIndex;
}
} else {
seen.set(arr[i], i);
}
}
return minIndex;
}
const arr3 = [3, 2, 1, 2, 4, 3];
console.log(findMinIndexWithSet(arr3));
Output
0
JavaScript Program for the Minimum Index of a Repeating Element in an Array
Given an array of integers arr[], The task is to find the index of the first repeating element in it i.e. the element that occurs more than once and whose index of the first occurrence is the smallest. In this article, we will find the minimum index of a repeating element in an array in JavaScript.
Examples:
Input: arr[] = {10, 5, 3, 4, 3, 5, 6}
Output: 5
Explanation: 5 is the first element that repeats
Input: arr[] = {6, 10, 5, 4, 9, 120, 4, 6, 10}
Output: 6
Explanation: 6 is the first element that repeats
Table of Content
- Brute force approach:
- Using an Object (Hash Map)
- Using a Set:
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