备忘录模式--示例代码

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define MEMENTO_LEN 30
int memento[MEMENTO_LEN]={0};//备忘录
int fibonacci_memento( int n){

  if(memento[n]!=-1){
    return memento[n];
  }
  
  int t=0;
   if(n<=1){
    t=n;
   }else{
    t=fibonacci_memento(n-1)+fibonacci_memento(n-2);
  }
  memento[n]=t;
  return t;
}
int fibonacci( int n){
  int t=0;
   if(n<=1){
    t=n;
   }else{
    t=fibonacci(n-1)+fibonacci(n-2);
  }
  return t;
}
void init(){
  for(int i=0;i<MEMENTO_LEN;i++)
  memento[i]=-1;
}
int main(){
  int i=0;
  clock_t start,end;
  init();
  start=clock();
  for(i=MEMENTO_LEN-1;i>=0;i--){
    fibonacci(i);
  }
  end=clock();
  printf("\nruntime=%ld-%ld\n",end,start);
  
  start=clock();
  for(i=MEMENTO_LEN-1;i>=0;i--){
    fibonacci_memento(i);
  }
  end=clock();
  printf("\nruntime=%ld-%ld\n",end,start);

  return 0;
}

typedef struct {
    int state;
} Memento;

typedef struct {
    int state;
    Memento* (*save)(void);
} Originator;

Memento* save(Originator* self) {
    Memento* m = malloc(sizeof(Memento));
    m->state = self->state;
    return m;
}

// 使用
Originator originator = { .state = 100, .save = save };
Memento* m = originator.save(&originator);
printf("Saved state: %d\n", m->state); // 输出 100