循环队列，4阶斐波那契数列

4阶斐波那契序列如下：f0=f1=f2=0, f3=1,…,fi=fi-1+fi-2+fi-3+fi-4，

利用容量为k=4的循环队列，构造序列的前n+1项（f0, f1 , f2 ,… fn ），要求满足fn ≤200而fn+1 >200。

#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 4

typedef struct {
    int *base;
    int front;
    int rear;
    int length;
}SqQueue;

SqQueue* InitQueue(){
    SqQueue *Q = (SqQueue*)malloc(sizeof(SqQueue));
    Q->base = (int*)malloc(sizeof(int)*MAXSIZE);
    if(!Q->base)
        exit(0);
    Q->front = 0;
    Q->rear = 0;
    Q->length = 0;
    return Q;
}

void EnQueue(SqQueue *Q, int e){
    if(Q->length >= MAXSIZE) return ; //队列已满
    Q->base[Q->rear] = e;
    Q->rear = (Q->rear+1) % MAXSIZE;
    Q->length++;
}

int Delete(SqQueue *Q){
    if(Q->length == 0) return 0;//队列为空
    int e = Q->base[Q->front];
    Q->front = (Q->front+1) % MAXSIZE;
    Q->length--;
    return e;
}

int Fib_4(SqQueue *Q, int n){
    if(n < 0) return -1;
    if(n < 3) return 0;
    if(n == 3) return 1;
    int cnt = 1;
    int temp = 0;
    while(cnt <= n-3){
        temp = Q->base[0] + Q->base[1] + Q->base[2] + Q->base[3];
        Delete(Q);
        EnQueue(Q, temp);
        cnt++;
    }
    return temp;
}

int Fib_4_digui(int n){ //不采用队列，用递归实现
    if(n < 0) return -1;
    if(n < 3) return 0;
    if(n == 3) return 1;
    return (Fib_4_digui(n-1) + Fib_4_digui(n-2) + Fib_4_digui(n-3) + Fib_4_digui(n-4));
}

int main()
{
  /*  int n = 0;
    while(Fib_4_digui(n-1) < 200){
        printf("Fib_4_dugui(%d)=%d\n", n, Fib_4_digui(n));
        n++;
    }*/
    SqQueue *Q = InitQueue();
    EnQueue(Q, 0);
    EnQueue(Q, 0);
    EnQueue(Q, 0);
    EnQueue(Q, 1);
    int temp = 0;
    printf("0 0 0 1");
    while(temp <= 200){
        temp = Q->base[0]+Q->base[1]+Q->base[2]+Q->base[3];
        printf(" %d", temp);
        Delete(Q);
        EnQueue(Q, temp);
    }
    return 0;
}