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  1. const fs = require("fs");
  2.  
  3. const input = fs.readFileSync(0, "utf8").trim().split(/\s+/);
  4. let a = BigInt(input[0]);
  5. let b = BigInt(input[1]);
  6.  
  7. function countDigitUpTo(n, d) {
  8.   if (n < 0n) return 0n;
  9.  
  10.   let total = 0n;
  11.   let factor = 1n;
  12.  
  13.   while (factor <= n) {
  14.     const tenFactor = factor * 10n;
  15.     const high = n / tenFactor;
  16.     const cur = (n / factor) % 10n;
  17.     const low = n % factor;
  18.  
  19.     if (cur > d) total += (high + 1n) * factor;
  20.     else if (cur === d) total += high * factor + (low + 1n);
  21.     else total += high * factor;
  22.  
  23.     factor *= 10n;
  24.   }
  25.   return total;
  26. }
  27.  
  28. function count369UpTo(n) {
  29.   if (n < 0n) return 0n;
  30.   return (
  31.     countDigitUpTo(n, 3n) +
  32.     countDigitUpTo(n, 6n) +
  33.     countDigitUpTo(n, 9n)
  34.   );
  35. }
  36.  
  37. const result = count369UpTo(b) - count369UpTo(a - 1n);
  38. console.log(result.toString());
  39.  
Success #stdin #stdout 0.06s 40736KB
comments (?)
stdin
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999999 10000000
stdout
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19200006
https://ideone.com/i14CZA
language:
Node.js (node 20.14)
created:
11 hours ago
visibility:
public

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