38 lines
1.0 KiB
D
38 lines
1.0 KiB
D
import std.stdio, std.algorithm, std.conv;
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string[] selfReferentialSeq(string n, string[] seen=[]) {
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static string[][string] cache;
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if (n in cache) return cache[n];
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if (canFind(seen, n)) return [];
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int[10] digit_count;
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foreach (d; n)
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digit_count[d - '0']++;
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string term;
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foreach_reverse (d; 0 .. 10)
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if (digit_count[d] > 0)
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term ~= text(digit_count[d], d);
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return cache[n] = [n] ~ selfReferentialSeq(term, [n] ~ seen);
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}
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void main() {
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enum int limit = 1_000_000;
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int max_len;
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int[] max_vals;
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foreach (n; 1 .. limit) {
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const seq = n.text().selfReferentialSeq();
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if (seq.length > max_len) {
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max_len = seq.length;
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max_vals = [n];
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} else if (seq.length == max_len)
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max_vals ~= n;
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}
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writeln("values: ", max_vals);
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writeln("iterations: ", max_len);
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writeln("sequence:");
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foreach (idx, val; max_vals[0].text().selfReferentialSeq())
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writefln("%2d %s", idx + 1, val);
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}
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