main.go

// Source: https://leetcode.com/problems/build-array-from-permutation
// Title: Build Array from Permutation
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Given a **zero-based permutation** `nums` (**0-indexed**), build an array `ans` of the **same length** where `ans[i] = nums[nums[i]]` for each `0 <= i < nums.length` and return it.
//
// A **zero-based permutation** `nums` is an array of **distinct** integers from `0` to `nums.length - 1` (**inclusive**).
//
// **Example 1:**
//
// ```
// Input: nums = [0,2,1,5,3,4]
// Output: [0,1,2,4,5,3]**
// Explanation: The array ans is built as follows:
// ans = [nums[nums[0]], nums[nums[1]], nums[nums[2]], nums[nums[3]], nums[nums[4]], nums[nums[5]]]
//     = [nums[0], nums[2], nums[1], nums[5], nums[3], nums[4]]
//     = [0,1,2,4,5,3]
// ```
//
// **Example 2:**
//
// ```
// Input: nums = [5,0,1,2,3,4]
// Output: [4,5,0,1,2,3]
// Explanation: The array ans is built as follows:
// ans = [nums[nums[0]], nums[nums[1]], nums[nums[2]], nums[nums[3]], nums[nums[4]], nums[nums[5]]]
//     = [nums[5], nums[0], nums[1], nums[2], nums[3], nums[4]]
//     = [4,5,0,1,2,3]
// ```
//
// **Constraints:**
//
// - `1 <= nums.length <= 1000`
// - `0 <= nums[i] < nums.length`
// - The elements in `nums` are **distinct**.
//
// **Follow-up:** Can you solve it without using an extra space (i.e., `O(1)` memory)?
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

func buildArray(nums []int) []int {
	n := len(nums)
	ans := make([]int, n)

	for i := range n {
		ans[i] = nums[nums[i]]
	}
	return ans
}