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.
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 . The second pair [3,4] means we have freq = 3 and val = 4 so we generate [4,4,4]. At the end the concatenation  + [4,4,4] is [2,4,4,4].
Input: nums = [1,1,2,3] Output: [1,3,3]
2 <= nums.length <= 100
nums.length % 2 == 0
1 <= nums[i] <= 100
Step by 2 each time to add pairs.
class Solution: def decompressRLElist(self, nums: List[int]) -> List[int]: results =  for i in range(1, len(nums), 2): freq = nums[i - 1] value = nums[i] for j in range(freq): results.append(value) return results
- Time Complexity: O(logN)
- Space Complexity: O(N)