Suddenly, whirling in the distance, you notice what looks like a massive, pixelated hurricane: a deadly spinlock. This spinlock isn't just consuming computing power, but memory, too; vast, digital mountains are being ripped from the ground and consumed by the vortex.

If you don't move quickly, fixing that printer will be the least of your problems.

Read the full puzzle.

using System.Collections.Generic;

namespace AdventOfCode.Y2017.Day17;

[ProblemName("Spinlock")]
class Solution : Solver {

    public object PartOne(string input) {
        var step = int.Parse(input);
        var nums = new List<int>() { 0 };
        var pos = 0;
        for (int i = 1; i < 2018; i++) {
            pos = (pos + step) % nums.Count + 1;
            nums.Insert(pos, i);
        }
        return nums[(pos + 1) % nums.Count];
    }

    public object PartTwo(string input) {
        var step = int.Parse(input);
        var pos = 0;
        var numsCount = 1;
        var res = 0;
        for (int i = 1; i < 50000001; i++) {
            pos = (pos + step) % numsCount + 1;
            if (pos == 1) {
                res = i;
            }
            numsCount++;
        }
        return res;
    }
}

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