1313. 解压缩编码列表

class Solution {
  public int[] decompressRLElist(int[] nums) {
      int size = 0;
      for(int i = 0; i < nums.length; i+=2){
          size += nums[i];
      }
      int arr[] = new int[size];
      int index = 0;
      for(int i = 0; i < nums.length; i+=2){
          int a = nums[i], b = nums[i+1];
          for(int j = 0; j < a; j++){
              arr[index++] = b;
          }
      }
      return arr;
  }
}