用栈实现递归函数的一个例子(C语言实现)

#include
#include
void *MemAlloc(unsigned int ulMemSize)
{
return malloc(ulMemSize);
}
void MemFree(void **ppvFree)
{
free(*ppvFree);
*ppvFree = 0;
}
/* 裴波那契数列非递归实现 */
/* 栈元素内存可以优化，在此不做优化， 仅仅供学习参考 */
unsigned int FibnoFunction(unsigned int ulNum)
{
unsigned int *pulStackBt;
unsigned int *pulStackTop;
unsigned int ulSumRet;
pulStackBt = MemAlloc(sizeof(unsigned int)*(ulNum+ 1));
if (pulStackBt == 0)
{
return -1;
}
/* 初始化栈 */
pulStackTop = pulStackBt + ulNum;
pulStackTop[0] = 0;
if (ulNum > 0)
{
pulStackTop[-1] = 1;
}
/* 依次出栈 */
while (pulStackTop > pulStackBt + 1)
{
pulStackTop[-2] = pulStackTop[-1] + pulStackTop[0];
pulStackTop--;
}
ulSumRet = *pulStackBt;
MemFree(&pulStackBt);
return ulSumRet;
}
int main(int args, unsigned char **ppargs)
{
unsigned int ulFebSum = 0;
for (ulFebSum = 0; ulFebSum < 15; ulFebSum++)
{
printf("FibnoFunction(%u) = %u\r\n", ulFebSum, FibnoFunction(ulFebSum));
}
return 0;
}

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