main.cpp

// Source: https://leetcode.com/problems/transformed-array
// Title: Transformed Array
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

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// You are given an integer array `nums` that represents a circular array. Your task is to create a new array `result` of the **same** size, following these rules:
// For each index `i` (where `0 <= i < nums.length`), perform the following **independent** actions:
//
// - If `nums[i] > 0`: Start at index `i` and move `nums[i]` steps to the **right** in the circular array. Set `result[i]` to the value of the index where you land.
// - If `nums[i] < 0`: Start at index `i` and move `abs(nums[i])` steps to the **left** in the circular array. Set `result[i]` to the value of the index where you land.
// - If `nums[i] == 0`: Set `result[i]` to `nums[i]`.
//
// Return the new array `result`.
//
// **Note:** Since `nums` is circular, moving past the last element wraps around to the beginning, and moving before the first element wraps back to the end.
//
// **Example 1:**
//
// Input: nums = [3,-2,1,1]
//
// Output: [1,1,1,3]
//
// Explanation:
//
// - For `nums[0]` that is equal to 3, If we move 3 steps to right, we reach `nums[3]`. So `result[0]` should be 1.
// - For `nums[1]` that is equal to -2, If we move 2 steps to left, we reach `nums[3]`. So `result[1]` should be 1.
// - For `nums[2]` that is equal to 1, If we move 1 step to right, we reach `nums[3]`. So `result[2]` should be 1.
// - For `nums[3]` that is equal to 1, If we move 1 step to right, we reach `nums[0]`. So `result[3]` should be 3.
//
// **Example 2:**
//
// Input: nums = [-1,4,-1]
//
// Output: [-1,-1,4]
//
// Explanation:
//
// - For `nums[0]` that is equal to -1, If we move 1 step to left, we reach `nums[2]`. So `result[0]` should be -1.
// - For `nums[1]` that is equal to 4, If we move 4 steps to right, we reach `nums[2]`. So `result[1]` should be -1.
// - For `nums[2]` that is equal to -1, If we move 1 step to left, we reach `nums[1]`. So `result[2]` should be 4.
//
// **Constraints:**
//
// - `1 <= nums.length <= 100`
// - `-100 <= nums[i] <= 100`
//
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#include <vector>

using namespace std;

class Solution {
 private:
  int mod(int val, int n) { return ((val % n) + n) % n; }

 public:
  vector<int> constructTransformedArray(vector<int>& nums) {
    int n = nums.size();

    // Init the result
    auto result = vector<int>(n);

    // Loop the numbers
    for (int i = 0; i < n; ++i) {
      auto num = nums[i];
      result[i] = nums[mod(i + num, n)];
    }

    return result;
  }
};