1313. Decompress Run-Length Encoded List*
https://leetcode.com/problems/decompress-run-length-encoded-list/
题目描述
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
C++ 实现 1
看例子更容易明白题目在说啥.
class Solution {
public:
vector<int> decompressRLElist(vector<int>& nums) {
vector<int> res;
for (int i = 0; i < nums.size() / 2; i ++) {
auto freq = nums[2 * i], val = nums[2 * i + 1];
vector<int> tmp(freq, val);
std::copy(tmp.begin(), tmp.end(), back_inserter(res));
}
return res;
}
};
C++ 实现 2
class Solution {
public:
vector<int> decompressRLElist(vector<int>& nums) {
vector<int> v;
for (int i = 0; i < nums.size(); i += 2) {
for (int j = 0; j < nums[i]; j++) {
v.push_back(nums[i+1]);
}
}
return v;
}
};