二叉树的建立与遍历方法

 

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<set>
#include<map>
#include<queue>
#include<vector>

using namespace std;

typedef struct node{
    char data;
    struct node *left, *right;
}node, *BiTree;

//创建一个二叉树
BiTree CreateBiTree(BiTree T){
    char ch;
    cin>>ch;
    if (ch == '#')
        T = NULL;
    else {
        T = new node;
        if (!T)
            exit(-1);
        T->data = ch;
        T->left = CreateBiTree(T->left);
        T->right = CreateBiTree(T->right);
    }
    return T;
}

//二叉树的先序遍历
void PreOrder(BiTree T){
    if (T){
        cout<<T->data<<" ";
        PreOrder(T->left);
        PreOrder(T->right);
    }
}

//二叉树的中序遍历
void InOrder(BiTree T){
    if (T){
        InOrder(T->left);
        cout<<T->data<<" ";
        InOrder(T->right);
    }
}

//二叉树的后序遍历
void PostOrder(BiTree T){
    if (T){
        PostOrder(T->left);
        PostOrder(T->right);
        cout<<T->data<<" ";
    }
}

//二叉树的层序遍历
void bfsOrder(BiTree T){
    queue<BiTree> q;
    q.push(T);
    while(!q.empty()){
        BiTree t = q.front();
        cout<<t->data<<" ";
        q.pop();
        if (t->left != NULL) q.push(t->left);
        if (t->right != NULL) q.push(t->right);
    }
}

int main()
{
    BiTree BTree;
    BTree = CreateBiTree(BTree);
    PreOrder(BTree);
    cout<<endl;
    InOrder(BTree);
    cout<<endl;
    PostOrder(BTree);
    cout<<endl;
    bfsOrder(BTree);
    cout<<endl;

    return 0;
}