二叉树的递归和非递归实现

来源：互联网发布：阿里云ecs地域选择编辑：程序博客网时间：2024/05/16 18:01
#include <stdio.h>#include <string.h>#include <stdlib.h>typedef struct BiTree{    int data;    struct BiTree* lchild;    struct BiTree* rchild;}BiTree, *PBiTree;typedef struct Stack{    BiTree* data[128];    int top;}Stack;void stack_init(Stack* pStack){    memset(pStack, 0, sizeof(Stack));    pStack->top = -1;}BiTree* stack_pop(Stack* pStack){    if(pStack->top == -1)        return NULL;    return pStack->data[pStack->top--];}BiTree* stack_get_top(Stack* pStack){    if(pStack->top == -1)        return NULL;    else        return pStack->data[pStack->top];}int stack_push(Stack* pStack, BiTree* pBiTree){    if(pStack->top == 127)        return 0;    pStack->data[++pStack->top] = pBiTree;    return 1;}int stack_is_empty(Stack* pStack){    return pStack->top == -1;}int bitree_create(BiTree** ppBiTree){    int data;    for(;;){        printf("输入节点的值:");        if(scanf("%d", &data) == 1)            break;        fflush(stdin);    }    if(data == 0){        (*ppBiTree) = NULL;        return 1;    }else{        (*ppBiTree) = (PBiTree)malloc(sizeof(BiTree));        if(!*ppBiTree){            perror("内存分配失败");            return 0;        }else{            memset(*ppBiTree, 0, sizeof(BiTree));            (*ppBiTree)->data = data;            bitree_create(&(*ppBiTree)->lchild);            bitree_create(&(*ppBiTree)->rchild);        }    }    return 1;}//释放二叉树void bitree_free(BiTree* pBiTree){    if(pBiTree){        bitree_free(pBiTree->lchild);        bitree_free(pBiTree->rchild);        free(pBiTree);        pBiTree = NULL;    }}/*先序遍历非递归算法*/void PreOrderTraverse(BiTree* pBiTree){    Stack stk;    BiTree* pb = pBiTree;    stack_init(&stk);    while(pb || !stack_is_empty(&stk)){        while(pb){            printf("%d ", pb->data);            stack_push(&stk, pb);            pb = pb->lchild;        }        pb = stack_pop(&stk);           pb = pb->rchild;    }}/*先序遍历递归算法*/void PreOrderTraverse2(BiTree* pBiTree){    if(pBiTree){        printf("%d ", pBiTree->data);//显示数据        PreOrderTraverse2(pBiTree->lchild);//访问左孩子        PreOrderTraverse2(pBiTree->rchild);//访问右孩子    }}/* 中序遍历递归算法 */void InOrderTraverse2(BiTree* pBiTree){    if(pBiTree){        InOrderTraverse2(pBiTree->lchild);        printf("%d ", pBiTree->data);        InOrderTraverse2(pBiTree->rchild);    }}/* 中序遍历递归算法2 */void InOrderTraverse3(BiTree* pBiTree){    Stack stk;    BiTree* pb = NULL;    stack_init(&stk);    pb = pBiTree;    while(pb || !stack_is_empty(&stk)){        if(pb){            stack_push(&stk, pb);//根指针进栈            pb = pb->lchild;//遍历左子树        }else{            //根指针出栈, 访问根结点, 遍历右子树            pb = stack_pop(&stk);            printf("%d ", pb->data);            pb = pb->rchild;        }    }}/* 中序遍历非递归算法 */void InOrderTraverse(BiTree* pBiTree){    Stack stk;    BiTree* pb = NULL;    stack_init(&stk);//保存结点的栈    stack_push(&stk, pBiTree);//根指针进栈    while(!stack_is_empty(&stk)){        while((pb=stack_get_top(&stk)))            stack_push(&stk, pb->lchild);//向左走到尽头        pb = stack_pop(&stk);//最后一个空指针出栈        if(!stack_is_empty(&stk)){            pb = stack_pop(&stk);//得到最后一个结点/左孩子            printf("%d ", pb->data);            stack_push(&stk, pb->rchild);//访问右孩子        }    }}/* 后序遍历非递归算法 */void PostOrderTraverse(BiTree* pBiTree){    Stack stk;    BiTree* pb = NULL;    BiTree* pre = NULL;    stack_init(&stk);    while(pBiTree || !stack_is_empty(&stk)){        while(pBiTree){            stack_push(&stk, pBiTree);            pBiTree = pBiTree->lchild;        }        pBiTree = stack_get_top(&stk);        if(!pBiTree->rchild || pBiTree->rchild == pre){            printf("%d ", pBiTree->data);            stack_pop(&stk);            pre = pBiTree;            pBiTree = NULL;        }else{            pBiTree = pBiTree->rchild;        }    }}/* 后序遍历递归算法 */void PostOrderTraverse2(BiTree* pBiTree){    if(pBiTree){        PostOrderTraverse(pBiTree->lchild);        PostOrderTraverse(pBiTree->rchild);        printf("%d ", pBiTree->data);    }}int main(void){    BiTree* pbt = NULL;    bitree_create(&pbt);    printf("\n");    printf("先序遍历非递归算法:\t");    PreOrderTraverse(pbt);    printf("\n");    printf("先序遍历递归算法:\t");    PreOrderTraverse2(pbt);    printf("\n");    printf("中序遍历非递归算法:\t");    InOrderTraverse(pbt);    printf("\n");    printf("中序遍历递归算法:\t");    InOrderTraverse2(pbt);    printf("\n");    //printf("中序遍历递归算法2:\t");    //InOrderTraverse3(pbt);    //printf("\n");    printf("后序遍历非递归算法:\t");    PostOrderTraverse(pbt);    printf("\n");    printf("后序遍历递归算法:\t");    PostOrderTraverse2(pbt);    printf("\n");    printf("\n");    bitree_free(pbt);    system("pause");    return 0;}
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