1313. Decompress Run Length Encoded List

# 1313. Decompress Run-Length Encoded List#

## 题目 #

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]
``````

Constraints:

• `2 <= nums.length <= 100`
• `nums.length % 2 == 0`
• `1 <= nums[i] <= 100`

## 解题思路 #

• 给定一个带编码长度的数组，要求解压这个数组。
• 简单题。按照题目要求，下标从 0 开始，奇数位下标为前一个下标对应元素重复次数，那么就把这个元素 append 几次。最终输出解压后的数组即可。

## 代码 #

``````
package leetcode

func decompressRLElist(nums []int) []int {
res := []int{}
for i := 0; i < len(nums); i += 2 {
for j := 0; j < nums[i]; j++ {
res = append(res, nums[i+1])
}
}
return res
}

``````

Sep 6, 2020