leetcode-1313-easy

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.

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

思路一：模拟遍历

public int[] decompressRLElist(int[] nums) {
    List<Integer> list = new ArrayList<>();

    for (int i = 0; i < nums.length; i += 2) {
        int feq = nums[i];
        int val = nums[i + 1];
        for (int j = 0; j < feq; j++) {
            list.add(val);
        }
    }

    int[] result = new int[list.size()];
    for (int i = 0; i < list.size(); i++) {
        result[i] = list.get(i);
    }

    return result;
}

原文地址：http://www.cnblogs.com/iyiluo/p/16829650.html