Exercise 5: Flatten 1 Level
Problem Statement
Create a function `flatten1(arr)` that flattens one-level nested arrays.
Sample Output:
flatten1([1, [2, 3], [4, 5]]) => [1, 2, 3, 4, 5] flatten1([[1, 2], [3, 4]]) => [1, 2, 3, 4]
Solution
const flatten1 = (arr) => arr.flat();Explanation
Goal:
- Input: array jisme kuch elements khud arrays ho sakte hain (
[1, [2, 3], 4]). - Output: ek simple array jisme first level ka nesting hata diya ho (
[1, 2, 3, 4]).
Line: const flatten1 = (arr) => arr.flat();
arr.flat()→ JavaScript ka built‑in method hai.- Default behavior: depth = 1, yani sirf 1 level tak flatten karega.
- Agar
arr = [1, [2, 3], [4, 5]]ho → result[1, 2, 3, 4, 5]. - Lekin agar
arr = [1, [2, [3]]]ho → result[1, 2, [3]](kyunki nested level 2 tak nahi jaata).
Real world:
- APIs se data kabhi‑kabhi nested arrays ke form me aata hai (e.g. pages ka array, har page ke results ka array).
- UI me values dikhane se pehle flatten karke simple list banana easy ho jata hai.