Submission #1516090

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Source Code Expand

import std.array;
import std.stdio;
import std.range;
import std.algorithm;
import std.format;
import std.bigint;
import std.functional;
import std.string;
import std.conv;

void main()
{
	long A, B;
	string input = readln();
	input.formattedRead("%s %s", &A, &B);
	solve(A - 1, B).writeln();
}

long solve(long A, long B)
{
	return (B - f(B.to!string) + 1) - (A - f(A.to!string) + 1);
}

long f(string n)
{
	long first = n.take(1).array.to!long;
	return iota(first + 1).filter!(x => x != 4 && x != 9).map!((x) {
		if ((x + 1) * (10 ^^ (n.length - 1)) - 1 <= n.to!long)
		{
			return g(n.length - 1);
		}
		else
		{
			return f(n[1 .. $]);
		}
	}).sum();
}

long g(long m)
{
	return 8 ^^ m;
}

Submission Info

Judge Result