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  1. #include <stdio.h>
  2. #include <time.h>
  3.  
  4. // 递归实现
  5. long long fib_recursive(int n) {
  6.     if (n == 1 || n == 2) return 1;
  7.     return fib_recursive(n - 1) + fib_recursive(n - 2);
  8. }
  9.  
  10. // 迭代实现（从1开始）
  11. long long fib_iterative(int n) {
  12.     if (n == 1 || n == 2) return 1;
  13.     long long a = 1, b = 1, c;
  14.     for (int i = 3; i <= n; i++) {
  15.         c = a + b;
  16.         a = b;
  17.         b = c;
  18.     }
  19.     return b;
  20. }
  21.  
  22. int main() {
  23.     int n = 40; // 测试较大的n值
  24.     clock_t start, end;
  25.     double time_used;
  26.     // 测试递归方法
  27.     start = clock();
  28.     long long result_recursive = fib_recursive(n);
  29.     end = clock();
  30.     time_used = ((double)(end - start)) / CLOCKS_PER_SEC;
  31.     printf("递归方法: F(%d) = %lld, 耗时: %f 秒\n", n, result_recursive, time_used);
  32.  
  33.     // 测试迭代方法
  34.     start = clock();
  35.     long long result_iterative = fib_iterative(n);
  36.     end = clock();
  37.     time_used = ((double)(end - start)) / CLOCKS_PER_SEC;
  38.     printf("迭代方法: F(%d) = %lld, 耗时: %f 秒\n", n, result_iterative, time_used);
  39.     return 0;
  40. }
Success #stdin #stdout 0.33s 5292KB
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Standard input is empty
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递归方法: F(40) = 102334155, 耗时: 0.319511 秒
迭代方法: F(40) = 102334155, 耗时: 0.000000 秒
https://ideone.com/gqPuVD
language:
C (gcc 8.3)
created:
5 days ago
visibility:
public

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