fork download 
  1. #include <stdio.h>
  2. unsigned rev(unsigned n) {
  3.   unsigned acc;
  4.   for (acc = 0; n; acc = acc * 10 + n % 10, n /= 10);
  5.   return acc;
  6. }
  7. struct found {unsigned count, first, second, error;};
  8. struct found f(unsigned n) {
  9.   unsigned a, b;
  10.   if (n == rev(n)) return (struct found){1, n};
  11.   for (a = n - 1, b = n + 1; ;a--, b++)
  12.     switch ((a == rev(a)) * 10 + (b == rev(b))) {
  13.     case 11: return (struct found){2, a, b};
  14.     case 10: return (struct found){1, a};
  15.     case 01: return (struct found){1, b};
  16.     case 00: break;
  17.     default: return (struct found){0, -1, -1, 1};
  18.     }
  19.   return (struct found){0, -1, -1, 2};
  20. }
  21. void g(unsigned n) {
  22.   struct found found = f(n);
  23.   printf("入力: %u\n", n);
  24.   switch (found.count) {
  25.   case 1: printf("出力: [%u]\n\n", found.first);break;
  26.   case 2: printf("出力: [%u, %u]\n\n", found.first, found.second);break;
  27.   default: printf("出力: []\n\n");
  28.   }
  29. }
  30. int main() {
  31.   g(0), g(17), g(100);
  32.   return 0;
  33. }
  34.  
Success #stdin #stdout 0s 5304KB
comments (?)
stdin 
Standard input is empty
stdout 
入力: 0
出力: [0]

入力: 17
出力: [22]

入力: 100
出力: [99, 101]
https://ideone.com/mWihci
language:
C (gcc 8.3)
created:
95 days ago
visibility:
secret

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!