fib.cpp

#include<stdio.h>
#include<time.h>

int fibnor(int a, int b, int n);
int fibfun(int a, int b, int n);
int fibweak(int a, int b, int n);

int main() {
  int a, b, n, res, k;
  int t = 10000;
  while(scanf("%d%d%d", &a, &b, &n) != - 1) {
    clock_t ts, te;
    ts = clock(NULL);
    for(int i = 1; i <= t; i ++ ) {
      k ++ ;
      res = fibnor(a, b, n);
    }
    te = clock(NULL);
    printf("nor:%d %ld\n", res, te - ts);
    
    ts = clock(NULL);
    for (int i = 1; i <= t; i ++ ) {
      k ++ ;
      res = fibfun(a, b, n);
    }
    te = clock(NULL);
    printf("fun:%d %ld\n", res, te - ts);
    
    ts = clock(NULL);
    for (int i = 1; i <= t;i ++ ) {
      k ++ ;
      res = fibweak(a, b, n);
    }
    te = clock(NULL);
    printf("weak:%d %ld\n", res, te - ts);
    
    printf("%d\n", k);
  }
  
  return 0;
}

int fibnor(int a, int b, int n) {
  int tmp;
  for(int i = 0; i < n; i ++ ) {
    tmp = b;
    b = a + b;
    a = tmp;
  }
  return a;
}

int fibfun(int a, int b, int n) {
  if(n <= 1) {
    return b;
  }
  else {
    return fibfun(b, a + b, n - 1);
  }
}

int fibweak(int a, int b, int n) {
  if (n == 1) {
    return a;
  } else if (n == 2) {
    return b;
  } else {
    return fibweak(a, b, n - 1) + fibweak(a, b, n - 2);
  }
}