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  1. #include <stdio.h>
  2.  
  3. // 1
  4. int fib1(int n) {
  5.     if (n == 0) return 0;
  6.     if (n == 1) return 1;
  7.  
  8.     int a = 0;
  9.     int b = 1; 
  10.     int next;
  11.  
  12.     for (int i = 2; i <= n; i++) {
  13.         next = a + b;
  14.         a = b;
  15.         b = next;
  16.     }
  17.     return b;
  18. }
  19.  
  20. // 2
  21. int fib2(int n) {
  22.     if (n == 0) return 0;
  23.     if (n == 1) return 1;
  24.  
  25.     int f[n + 1];
  26.     f[0] = 0;
  27.     f[1] = 1;
  28.  
  29.     for (int i = 2; i <= n; i++) {
  30.         f[i] = f[i - 1] + f[i - 2];
  31.     }
  32.     return f[n];
  33. }
  34.  
  35. // 3
  36. int fib3(int n) {
  37.     if (n == 0) return 0;
  38.     if (n == 1) return 1;
  39.     return fib3(n - 1) + fib3(n - 2);
  40. }
  41.  
  42. int main(void) {
  43.     int n;
  44.  
  45.     scanf("%d", &n);
  46.  
  47.     printf("1: %d\n", fib1(n));
  48.     printf("2: %d\n", fib2(n));
  49.     printf("3: %d\n", fib3(n));
  50.  
  51.     return 0;
  52. }
Success #stdin #stdout 0s 5288KB
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stdin
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3
stdout
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1: 2
2: 2
3: 2
https://ideone.com/TG3rjF
language:
C (gcc 8.3)
created:
5 days ago
visibility:
public

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