85 lines
2.5 KiB
C#
85 lines
2.5 KiB
C#
string[] lines = """
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7 6 4 2 1
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1 2 7 8 9
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9 7 6 2 1
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1 3 2 4 5
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8 6 4 4 1
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1 3 6 7 9
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""".Split('\n', StringSplitOptions.RemoveEmptyEntries);
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// string[] lines = System.IO.File.ReadAllLines("input.txt");
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int levelsSafe = 0;
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foreach (string input in lines)
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{
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LinkedList<int> connected = new LinkedList<int>();
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var levels = input.Split(' ', StringSplitOptions.RemoveEmptyEntries).Select(int.Parse);
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foreach (var paredLevel in levels)
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{
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connected.AddLast(paredLevel);
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}
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Console.Write($"Testing {input} = ");
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var safe = TestLevel(connected);
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Console.WriteLine($"{(safe ? "Safe" : "Unsafe")}");
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levelsSafe += safe ? 1 : 0;
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}
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Console.WriteLine(levelsSafe);
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bool TestLevel(LinkedList<int> linkedList)
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{
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int unsafeCount = 0;
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var node = linkedList.First;
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List<LevelDirection> directions = new List<LevelDirection>();
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while (node != null)
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{
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bool safeRange = node switch
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{
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{ Previous: not null, Next: not null }
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=> InsideRange2(node.Previous.Value, node.Value, node.Next.Value),
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{ Previous: not null, Next: null }
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=> InsideRange(node.Previous.Value, node.Value),
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{ Previous: null, Next: not null }
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=> InsideRange(node.Next.Value, node.Value),
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_ => throw new InvalidOperationException()
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};
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if(safeRange is false)
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{
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unsafeCount++;
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}
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if (node.Next is not null)
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{
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directions.Add(node.Value > node.Next.Value ? LevelDirection.Increasing : LevelDirection.Decreasing);
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}
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node = node.Next;
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}
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bool allIncreasing = directions.All(x => x == LevelDirection.Increasing);
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bool allDecreasing = directions.All(x => x == LevelDirection.Decreasing);
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Console.Write($" {unsafeCount}|{allIncreasing}|{allDecreasing} ");
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return ((allIncreasing || allDecreasing) && unsafeCount == 0) || (allIncreasing == false && allDecreasing == false);
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bool InsideRange(int current, int target)
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{
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var abs = Math.Abs(current - target);
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return abs is >= 1 and <= 3;
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}
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bool InsideRange2(int prev, int current, int next)
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{
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var p = Math.Abs(prev - current);
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var n = Math.Abs(next - current);
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return p is >= 1 and <= 3 && n is >= 1 and <= 3;
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}
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}
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enum LevelDirection
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{
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Increasing,
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Decreasing
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} |