2626-array-reduce-transformation.ts

// Title: Array Reduce Transformation
// Description:
//     Given an integer array nums, a reducer function fn, and an initial 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, nums[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.
// Link: https://leetcode.com/problems/array-reduce-transformation/

type Fn = (accum: number, curr: number) => number;

function reduce(nums: number[], fn: Fn, init: number): number {
  let result = init;

  for (const num of nums) {
    result = fn(result, num);
  }

  return result;
}