1.二叉树的创建、先中后遍历、各个节点度的个数、深度

程序代码：

  1 #include<stdio.h>2 #include<string.h>3 #include<stdlib.h>4 typedef char datatype;5 typedef struct node6 {7     datatype data;8     struct node *lchild;9     struct node *rchild;10 }*Btree;11 //创建节点12 Btree create_node()13 {14     Btree s=(Btree)malloc(sizeof(struct node));15     if(NULL==s)16         return NULL;17     s->data='\0';18     s->lchild=s->rchild=NULL;19     return s;20 }21 //创建树22 Btree create_tree()23 {24     datatype element;25     printf("please enter element:");26     scanf(" %c",&element);27     if(element=='#')28         return NULL;29     //创建节点30     Btree tree=create_node();31     tree->data=element;32     //递归创建节点左孩子33     puts("左");34     tree->lchild=create_tree();35     //递归创建节点右孩子36     puts("右");37     tree->rchild=create_tree();38     return tree;39 }40 //先序遍历41 void output_first(Btree tree)42 {43     if(NULL==tree)44         return;45     printf("%c",tree->data);46     output_first(tree->lchild);47     output_first(tree->rchild);48 }49 //中序遍历50 void output_mid(Btree tree)51 {52     if(NULL==tree)53         return;54     output_mid(tree->lchild);55     printf("%c",tree->data);56     output_mid(tree->rchild);57 }58 //后序遍历59 void output_last(Btree tree)60 {61     if(NULL==tree)62         return;63     output_last(tree->lchild);64     output_last(tree->rchild);65     printf("%c",tree->data);66 }67 //计算二叉树节点个数68 void Count(Btree tree,int *n0,int *n1,int *n2)69 {70     if(NULL==tree)71         return;72     if(tree->lchild==NULL&&tree->rchild==NULL)73         ++*n0;74     else if(tree->lchild!=NULL&&tree->rchild!=NULL)75         ++*n2;76     else77         ++*n1;78     Count(tree->lchild,n0,n1,n2);79     Count(tree->rchild,n0,n1,n2);80 }81 //计算深度82 int high(Btree tree)83 {84     if(NULL==tree)85         return 0;86     int left=1+high(tree->lchild);87     int right=1+high(tree->rchild);88     return left>right?left:right;89 }90 int main(int argc, const char *argv[])91 {92     //创建树93     Btree tree=create_tree();94     //先序遍历95     output_first(tree);96     puts("");97     //中序遍历98     output_mid(tree);99     puts("");
100     //后序遍历
101     output_last(tree);
102     puts("");
103     //计算二叉树节点个数
104     int n0=0,n1=0,n2=0;
105     Count(tree,&n0,&n1,&n2);
106     printf("n0=%d n1=%d n2=%d n=%d\n",n0,n1,n2,n0+n1+n2);
107     //计算深度
108     int high_tree=high(tree);
109     printf("%d\n",high_tree);
110     return 0;
111 }    

运行结果：