Algo. Build Array from Permutation

Source

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.

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.

Solution

``````public class Solution {
public int[] BuildArray(int[] nums) {
var res = new int[nums.Length];
for (int i = 0; i < nums.Length; i++) {
res[i] = nums[nums[i]];
}
return res;
}
}``````
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