# 2632. Curry

###### tags: `leetcode 30 days js challenge` `Medium`

[2632. Curry](https://leetcode.com/problems/curry/)

### 題目描述

Given a function `fn`, return a **curried** version of that function.

A **curried** function is a function that accepts fewer or an equal number of parameters as the original function and returns either another **curried** function or the same value the original function would have returned.

In practical terms, if you called the original function like `sum(1,2,3)`, you would call the curried version like `csum(1)(2)(3)`, `csum(1)(2,3)`, `csum(1,2)(3)`, or `csum(1,2,3)`. All these methods of calling the **curried** function should return the same value as the original.

### 範例

**Example 1:**

Input: 
fn = function sum(a, b, c) { return a + b + c; }
inputs = [[1],[2],[3]]
Output: 6
Explanation:
The code being executed is:
const curriedSum = curry(fn);
curriedSum(1)(2)(3) === 6;
curriedSum(1)(2)(3) should return the same value as sum(1, 2, 3).

**Example 2:**

Input:
fn = function sum(a, b, c) { return a + b + c; }
inputs = [[1,2],[3]]
Output: 6
Explanation:
curriedSum(1, 2)(3) should return the same value as sum(1, 2, 3).

**Example 3:**

Input:
fn = function sum(a, b, c) { return a + b + c; }
inputs = [[],[],[1,2,3]]
Output: 6
Explanation:
You should be able to pass the parameters in any way, including all at once or none at all.
curriedSum()()(1, 2, 3) should return the same value as sum(1, 2, 3).

**Example 4:**

Input:
fn = function life() { return 42; }
inputs = [[]]
Output: 42
Explanation:
currying a function that accepts zero parameters should effectively do nothing.
curriedLife() === 42

**Constraints**:

- `1 <= inputs.length <= 1000`
- 0 <= `inputs[i][j]` <= 10⁵
- `0 <= fn.length <= 1000`
- `inputs.flat().length == fn.length`
- `function parameters explicitly defined`

### 解答

#### TypeScript

function curry(fn: Function): Function {
  const accumulator: unknown[] = [];

  return function curried(...args: unknown[]) {
    args.forEach((arg) => accumulator.push(arg));
    if (accumulator.length === fn.length) {
      return fn(...accumulator);
    }

    return (...nextArgs: unknown[]) => curried(...nextArgs);
  };
}

> 學這麼久今天才知道 `function.length` 是參數的數量ㄏㄏ
> [name=Sheep][time=Sun, May 14, 2023]

### Reference

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