48 lines
1.1 KiB
D
48 lines
1.1 KiB
D
import std.stdio, std.bigint, std.range, std.algorithm;
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struct Filtered(R1, R2) if (is(ElementType!R1 == ElementType!R2)) {
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R1 s1;
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R2 s2;
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alias ElementType!R1 T;
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T front, source, filter;
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this(R1 r1, R2 r2) {
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s1 = r1;
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s2 = r2;
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source = s1.front;
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filter = s2.front;
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popFront;
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}
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static immutable empty = false;
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void popFront() {
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while (true) {
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if (source > filter) {
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s2.popFront;
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filter = s2.front;
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continue;
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} else if (source < filter) {
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front = source;
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s1.popFront;
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source = s1.front;
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break;
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}
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s1.popFront;
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source = s1.front;
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}
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}
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}
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auto filtered(R1, R2)(R1 r1, R2 r2) // Helper function.
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if (isInputRange!R1 && isInputRange!R2 &&
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is(ElementType!R1 == ElementType!R2)) {
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return Filtered!(R1, R2)(r1, r2);
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}
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void main() {
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auto squares = 0.sequence!"n".map!(i => i.BigInt ^^ 2);
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auto cubes = 0.sequence!"n".map!(i => i.BigInt ^^ 3);
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filtered(squares, cubes).drop(20).take(10).writeln;
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}
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