day 9, part 2 solution
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@ -33,14 +33,43 @@ namespace AdventOfCode {
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throw new Exception("didn't find an invalid int");
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}
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static long CalculateWeakness(List<long> longs, int minIndex, int maxIndex) {
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long largest = 0;
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long smallest = long.MaxValue;
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for (int i = minIndex; i <= maxIndex; i++) {
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if (longs[i] > largest) {
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largest = longs[i];
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}
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if (longs[i] < smallest) {
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smallest = longs[i];
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}
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}
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return smallest + largest;
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}
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static long FindWeakness(List<long> longs, long target) {
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for (int i = 0; i < longs.Count() - 1; i++) {
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long total = 0;
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for (int j = i; j < longs.Count() && total < target; j++) {
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total += longs[j];
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if (total == target) {
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return CalculateWeakness(longs, i, j);
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}
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}
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}
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throw new Exception("didn't find a weakness");
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}
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static long Part1() {
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string[] input = File.ReadAllLines(Util.RootDir + "day09.txt");
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List<long> longs = input.ToList().Select(long.Parse).ToList();
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return FindInvalid(longs, 25);
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}
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static int Part2() {
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return -1;
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static long Part2(long target) {
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string[] input = File.ReadAllLines(Util.RootDir + "day09.txt");
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List<long> longs = input.ToList().Select(long.Parse).ToList();
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return FindWeakness(longs, target);
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}
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[Fact]
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@ -69,8 +98,9 @@ namespace AdventOfCode {
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List<long> longs = example.ToList().Select(long.Parse).ToList();
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Assert.Equal(127, FindInvalid(longs, 5));
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Assert.Equal(50047984, Part1());
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Assert.Equal(-1, Part2());
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long invalidNumber = Part1();
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Assert.Equal(50047984, invalidNumber);
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Assert.Equal(5407707, Part2(invalidNumber));
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}
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}
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}
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