LeetCode-in-Java

2635. Apply Transform Over Each Element in Array

Easy

Given an integer array arr and a mapping function fn, return a new array with a transformation applied to each element.

The returned array should be created such that returnedArray[i] = fn(arr[i], i).

Please solve it without the built-in Array.map method.

Example 1:

Input: arr = [1,2,3], fn = function plusone(n) { return n + 1; }

Output: [2,3,4]

Explanation:

const newArray = map(arr, plusone); // [2,3,4]

The function increases each value in the array by one.

Example 2:

Input: arr = [1,2,3], fn = function plusI(n, i) { return n + i; }

Output: [1,3,5]

Explanation: The function increases each value by the index it resides in.

Example 3:

Input: arr = [10,20,30], fn = function constant() { return 42; }

Output: [42,42,42]

Explanation: The function always returns 42.

Constraints:

• 0 <= arr.length <= 1000
• -109 <= arr[i] <= 109
• fn returns a number

Solution

function map(arr: number[], fn: (n: number, i: number) => number): number[] {
    const res: number[] = []
    for (let i = 0; i < arr.length; i++) {
        res.push(fn(arr[i], i))
    }
    return res
}

export { map }

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