1313. 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.

题意描述得有点让人难理解，举例说明nums=[1,2,3,4]，那么但是1个2和3个4这两个子数组连接得到[2], [4, 4, 4] = [2, 4, 4, 4]

class Solution(object):
    def decompressRLElist(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
        """
        ans = []
        for i in range(0, len(nums), 2):
            ans += [nums[i + 1]] * nums[i]
        return ans