C语言二叉树常见操作详解【前序,中序,后序,层次遍历及非递归查找,统计个数,比较,求深度】

#define LENGTH 100
typedef char datatype;
typedef struct node{
  datatype data;
  int lchild,rchild;
  int parent;
}Node;
Node tree[LENGTH];
int length;
int root;

typedef char datatype;
typedef struct BinNode{
  datatype data;
  struct BinNode* lchild;
  struct BinNode* rchild;
}BinNode;
typedef BinNode* bintree;     //bintree本身是个指向结点的指针

void preorder(bintree t){
  if(t){
    printf("%c ",t->data);
    preorder(t->lchild);
    preorder(t->rchild);
  }
}

#define SIZE 100
typedef struct seqstack{
  bintree data[SIZE];
  int tag[SIZE];  //为后续遍历准备的
  int top;   //top为数组的下标
}seqstack;
void push(seqstack *s,bintree t){
  if(s->top == SIZE){
    printf("the stack is full\n");
  }else{
    s->top++;
    s->data[s->top]=t;
  }
}
bintree pop(seqstack *s){
  if(s->top == -1){
    return NULL;
  }else{
    s->top--;
    return s->data[s->top+1];
  }
}

void preorder_dev(bintree t){
  seqstack s;
  s.top = -1;   //因为top在这里表示了数组中的位置，所以空为-1
  if(!t){
    printf("the tree is empty\n");
  }else{
    while(t || s.stop != -1){
      while(t){  //只要结点不为空就应该入栈保存，与其左右结点无关
         printf("%c ",t->data);
        push(&s,t);
        t= t->lchild;
      }
      t=pop(&s);
      t=t->rchild;
    }
  }
}

void midorder(bintree t){
  seqstack s;
  s.top = -1;
  if(!t){
    printf("the tree is empty!\n");
  }else{
    while(t ||s.top != -1){
      while(t){
        push(&s,t);
        t= t->lchild;
      }
      t=pop(&s);
      printf("%c ",t->data);
      t=t->rchild;
    }
  }
}

void postorder_dev(bintree t){
  seqstack s;
  s.top = -1;
  if(!t){
    printf("the tree is empty!\n");
  }else{
    while(t || s.top != -1){  //栈空了的同时t也为空。
      while(t){
        push(&s,t);
        s.tag[s.top] = 0;  //设置访问标记，0为第一次访问，1为第二次访问
        t= t->lchild;
      }
      if(s.tag[s.top] == 0){ //第一次访问时，转向同层右结点
        t= s.data[s.top];  //左走到底时t是为空的，必须有这步！
        s.tag[s.top]=1;
        t=t->rchild;
      }else {
        while (s.tag[s.top] == 1){ //找到栈中下一个第一次访问的结点，退出循环时并没有pop所以为其左子结点
          t = pop(&s);
          printf("%c ",t->data);
        }
        t = NULL; //必须将t置空。跳过向左走，直接向右走
      }
    }
  }
}

#define MAX 1000
typedef struct seqqueue{
  bintree data[MAX];
  int front;
  int rear;
}seqqueue;
void enter(seqqueue *q,bintree t){
  if(q->rear == MAX){
    printf("the queue is full!\n");
  }else{
    q->data[q->rear] = t;
    q->rear++;
  }
}
bintree del(seqqueue *q){
  if(q->front == q->rear){
    return NULL;
  }else{
    q->front++;
    return q->data[q->front-1];
  }
}

void level_tree(bintree t){
  seqqueue q;
  bintree temp;
  q.front = q.rear = 0;
  if(!t){
    printf("the tree is empty\n");
    return ;
  }
  enter(&q,t);
  while(q.front != q.rear){
    t=del(&q);
    printf("%c ",t->data);
    if(t->lchild){
      enter(&q,t->lchild);
    }
    if(t->rchild){
      enter(&q,t->rchild);
    }
  }
}

//递归调用，不存点，想的时候只关注于一个点，因为还会回来的，不要跟踪程序运行，否则容易多加循环
void createtree(bintree *t){
  datatype c;
  if((c=getchar()) == '#')
    *t = NULL;
  else{
    *t = (bintree)malloc(sizeof(BinNode));
    (*t)->data = c;
    createtree(&(*t)->lchild);
    createtree(&(*t)->rchild);
  }
}

bintree search_tree(bintree t,datatype x){
  if(!t){
    return NULL;
  }
  if(t->data == x){
    return t;
  }else{
    if(!search_tree(t->lchild,x)){
      return search_tree(t->rchild,x);
    }
    return t;
  }
}

int count_tree(bintree t){
  if(t){
    return (count_tree(t->lchild)+count_tree(t->rchild)+1);
  }
  return 0;
}

int is_equal(bintree t1,bintree t2){
  if(!t1 && !t2){   //都为空就相等
    return 1;
  }
  if(t1 && t2 && t1->data == t2->data){   //有一个为空或数据不同就不判断了
    if(is_equal(t1->lchild,t2->lchild))
      if(is_equal(t1->rchild,t2->rchild)){
        return 1;
      }
  }
  return 0;
}

int hight_tree(bintree t){
  int h,left,right;
  if(!t){
    return 0;
  }
  left = hight_tree(t->lchild);
  right = hight_tree(t->rchild);
  h = (left>right?left:right)+1;
  return h;
}