Submission #334136

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Source Code Expand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Solution {
    class Solution {
        static ulong A, B;
        static ulong[] s;
        static void Main(string[] args) {
            ulong[] r = ReadAsUlong();
            A = r[0];
            B = r[1];
            s = new ulong[19];
            for (int i = 1; i < 19; i++) {
                s[i] = 8 * s[i - 1] + 2 * (ulong)Math.Pow(10, i - 1);
            }
            Console.WriteLine(f(B) - f(A-1));
        }

        static ulong f(ulong n) {
            if (n == 0)
                return 0;

            int digit = 0; // 桁数
            ulong temp = n;
            while (temp != 0) {
                digit++;
                temp /= 10;
            }

            ulong top = n / (ulong)Math.Pow(10, digit - 1);
            ulong sum;
            if (top == 9) {
                sum = (ulong)(top - 1) * s[digit - 1] + (ulong)Math.Pow(10, digit - 1) + 1;
            }
            else if (top == 4) {
                sum = (ulong)4 * s[digit - 1] + 1;
            }
            else if (top <= 3) {
                sum = (ulong)top * s[digit - 1];
            }
            else {
                sum = (ulong)(top - 1) * s[digit - 1] + (ulong)Math.Pow(10, digit - 1);
            }

            return (top == 4 || top == 9) ?
                sum + (n - top * (ulong)Math.Pow(10, digit - 1)) :
                sum + f(n - top * (ulong)Math.Pow(10, digit - 1));
        }
        static int[] ReadAsInt() { return Console.ReadLine().Trim().Split(' ').Select(int.Parse).ToArray(); }
        static long[] ReadAsLong() { return Console.ReadLine().Trim().Split(' ').Select(long.Parse).ToArray(); }
        static ulong[] ReadAsUlong() { return Console.ReadLine().Trim().Split(' ').Select(ulong.Parse).ToArray(); }
        static float[] ReadAsFloat() { return Console.ReadLine().Trim().Split(' ').Select(float.Parse).ToArray(); }
    }
}

Submission Info

Judge Result