LeetCode : Decompress Run-Length Encoded List

We are given a list nums of integers representing a list compressed with run-length encoding.

Consider each adjacent pair of elements [freq, val] = [nums[2*i], nums[2*i+1]] (with i >= 0). For each such pair, there are freq elements with value val concatenated in a sublist. Concatenate all the sublists from left to right to generate the decompressed list.

Return the decompressed list.

Example 1:
Input: nums = [1,2,3,4]
Output: [2,4,4,4]
Explanation: The first pair [1,2] means we have freq = 1 and val = 2 so we generate the array [2].
The second pair [3,4] means we have freq = 3 and val = 4 so we generate [4,4,4].
At the end the concatenation [2] + [4,4,4] is [2,4,4,4].

Example 2:
Input: nums = [1,1,2,3]
Output: [1,3,3]

class Solution {
   public int[] decompressRLElist(int[] nums) {
       List target = new ArrayList();
       for(int i = 1; i < nums.length; i=i+2) {
           for (int j = 0; j < nums[i-1]; j++){
               target.add(nums[i]);
           }
       }

       int[] result = new int[target.size()];
       for(int i = 0 ; i < result.length; i++){
           result[i] = (int)target.get(i);
       }
       return result;
   }
}

• ArrayList to int[]