2626. Array Reduce Transformation
Given an integer array nums, a reducer function fn, and an intial value init, return a reduced array.
A reduced array is created by applying the following operation: val = fn(init, nums[0]), val = fn(val, nums[1]), val = fn(val, arr[2]), … until every element in the array has been processed. The final value of val is returned.
If the length of the array is 0, it should return init.
Please solve it without using the built-in Array.reduce method.
Example 1.
Input:
nums = [1,2,3,4]
fn = function sum(accum, curr) { return accum + curr; }
init = 0
Output: 10
Explanation:
initially, the value is init=0.
(0) + nums[0] = 1
(1) + nums[1] = 3
(3) + nums[2] = 6
(6) + nums[3] = 10
The final answer is 10.Example 2
Input:
nums = [1,2,3,4]
fn = function sum(accum, curr) { return accum + curr * curr; }
init = 100
Output: 130
Explanation:
initially, the value is init=100.
(100) + nums[0]^2 = 101
(101) + nums[1]^2 = 105
(105) + nums[2]^2 = 114
(114) + nums[3]^2 = 130
The final answer is 130.Example 3
Input:
nums = []
fn = function sum(accum, curr) { return 0; }
init = 25
Output: 25
Explanation: For empty arrays, the answer is always init.
Approach
Implementing Array.reduce() method.
We are given three arguments nums array, callbackFn, initialValue
firstly, if there is no elements in the array the reduce function should return the given initial value.
secondly, by looping through the nums array we can get each elements in the nums array and Since, the callbackFn needs 2 arguments which are accumulator and currentValue
this accumulator will be the new initial value made from every loop of array.
currentValue will be the index of element in the array
Lastly, In the loop of the array we need to update the value for the accumulator
How i Solved the Problem
/**
* @param {number[]} nums
* @param {Function} fn
* @param {number} init
* @return {number}
*/
var reduce = function (nums, fn, init) {
// Array is consist of numbers so initial value will be given init
let val = init;
// For Empty arrays, the answer is always init.
if (nums.length === 0) return init;
// fn() always have 2 arguments which are (accumulator , currentValue)
for (let i = 0; i < nums.length; i++) {
val = fn(val, nums[i]);
}
return val;
};