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 node
  6 {
  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     else
 77         ++*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：