数据结构二叉树的实现与三种遍历

// 实现二叉树的先序、中序和后序遍历

#define MAX 30 //二叉树中最多结点数

#define NULL 0

#include

#include

typedef struct btnode //二叉树的结点类型

{

char data;

struct btnode *lchild,*rchild;

}bttree;

bttree *cre_tree(char *str,int i,int m) //将字符串中的第i个字符到第个m字符作为数据生成对应的满二叉树

{

bttree *p;

if(i>m) //无效结点

return NULL;

p=(bttree *)malloc(sizeof(bttree)); //生成新结点

p->data=str[i];

p->lchild=cre_tree(str,2*i+1,m); //创建左子树

p->rchild=cre_tree(str,2*i+2,m); //创建右子树

return p;

}

void lev_order(char s[],int n) //层次遍历,即输出字符数组的元素{

int i;

for(i=0;i

{

printf("%c",s[i]);

printf("->");

}

}

void preorder(bttree *t) //先序遍历二叉树

{

if(t!=NULL)

{

printf("%c",t->data);

if(t->lchild)

{

printf("->");

preorder(t->lchild);

}

if(t->rchild)

{

printf("->");

preorder(t->rchild);

}

}

}

void inorder(bttree *t) //中序遍历二叉树{ if(t!=NULL)

{

inorder(t->lchild);

printf("%c",t->data);

printf("->");

inorder(t->rchild);

}

}

void postorder(bttree *t) //后序遍历二叉树{ if(t!=NULL)

{

postorder(t->lchild);

postorder(t->rchild);

printf("%c",t->data);

printf("->");

}

}

main() //主函数

{

int i,n;

char str[MAX];

bttree *root; //指向根结点的指针

printf("please input a bttree node number:\n");

scanf("%d",&n);

getchar(); //输入数字

printf("please input a string which length is %d:",n); for(i=0;i

str[i]=getchar();

printf("\n\n");

root=cre_tree(str,0,n); //生成二叉树

printf("the tree is already created\n");

//printf("lev_order before swapping:");

//lev_order(root,n);

//printf("\n");

printf("lev_order before swapping:");

lev_order(str,n);

printf("\n");

printf("the result after preorder processing:"); //先序遍历结果preorder(root);

printf("\n");

printf("the result after inorder processing:"); //中序遍历结果

inorder(root);

printf("\n");

printf("the result after postorder processing:"); //后序遍历结果postorder(root);

printf("\n\n");

}