40 lines
802 B
D
40 lines
802 B
D
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import std;
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void main()
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{
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File("input", "r").byLine.map!(to!int).array.multiply3EntriesThatSumTo(2020).writeln;
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}
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int multiply3EntriesThatSumTo(int[] input, int sum)
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{
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foreach (key1; input)
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{
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foreach (key2; input)
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{
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if (key2 == key1)
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{
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continue;
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}
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foreach (key3; input)
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{
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if (key3 == key1 || key3 == key2)
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{
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continue;
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}
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if (key1 + key2 + key3 == sum)
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{
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return key1 * key2 * key3;
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}
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}
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}
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}
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return 0;
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}
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unittest
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{
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auto input = [1721, 979, 366, 299, 675, 1456];
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assert(input.multiply3EntriesThatSumTo(2020) == 241_861_950);
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}
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