1313. Decompress Run-Length Encoded List.cpp

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



class Solution {
public:
    vector<int> decompressRLElist(vector<int>& nums) {
        int n=nums.size();
        vector<int> v;
        for(int i=0;i<n;i+=2){
            int freq=nums[i];
            int val=nums[i+1];
            while(freq--){
                v.push_back(val);
            }
        }
        return v;
    }
};