# 1389. Create Target Array in the Given Order

## Description

Given two arrays of integers nums and index. Your task is to create target array under the following rules:

• Initially target array is empty.
• From left to right read nums[i] and index[i], insert at index index[i] the value nums[i] in target array.
• Repeat the previous step until there are no elements to read in nums and index.

Return the target array.

It is guaranteed that the insertion operations will be valid.

Example 1:

Input: nums = [0,1,2,3,4], index = [0,1,2,2,1]
Output: [0,4,1,3,2]
Explanation:
nums       index     target
0            0        [0]
1            1        [0,1]
2            2        [0,1,2]
3            2        [0,1,3,2]
4            1        [0,4,1,3,2]


Example 2:

Input: nums = [1,2,3,4,0], index = [0,1,2,3,0]
Output: [0,1,2,3,4]
Explanation:
nums       index     target
1            0        [1]
2            1        [1,2]
3            2        [1,2,3]
4            3        [1,2,3,4]
0            0        [0,1,2,3,4]


Example 3:

Input: nums = [1], index = [0]
Output: [1]


Constraints:

• 1 <= nums.length, index.length <= 100
• nums.length == index.length
• 0 <= nums[i] <= 100
• 0 <= index[i] <= i

## Solutions

Solution 1: Simulation

We create a list $target$ to store the target array. Since the problem guarantees that the insertion position always exists, we can directly insert in the given order into the corresponding position.

The time complexity is $O(n^2)$, and the space complexity is $O(n)$. Where $n$ is the length of the array.

• class Solution {
public int[] createTargetArray(int[] nums, int[] index) {
int n = nums.length;
List<Integer> target = new ArrayList<>();
for (int i = 0; i < n; ++i) {
}
// return target.stream().mapToInt(i -> i).toArray();
int[] ans = new int[n];
for (int i = 0; i < n; ++i) {
ans[i] = target.get(i);
}
return ans;
}
}

• class Solution {
public:
vector<int> createTargetArray(vector<int>& nums, vector<int>& index) {
vector<int> target;
for (int i = 0; i < nums.size(); ++i) {
target.insert(target.begin() + index[i], nums[i]);
}
return target;
}
};

• class Solution:
def createTargetArray(self, nums: List[int], index: List[int]) -> List[int]:
target = []
for x, i in zip(nums, index):
target.insert(i, x)
return target


• func createTargetArray(nums []int, index []int) []int {
target := make([]int, len(nums))
for i, x := range nums {
copy(target[index[i]+1:], target[index[i]:])
target[index[i]] = x
}
return target
}

• function createTargetArray(nums: number[], index: number[]): number[] {
const ans: number[] = [];
for (let i = 0; i < nums.length; i++) {
ans.splice(index[i], 0, nums[i]);
}
return ans;
}