二叉树建立和遍历

闲着整理出来。

#include <stdio.h>
#include <string.h>
#include <iostream>
using namespace std;

struct Node {
    int date;
    Node *lChild, *rChild;
};

int n;

Node *create(int i) { // 建树
    Node *root;
    root = new Node();
    root->date = i;
    if (2*i <= n)
        root->lChild = create(2*i);
    else root->lChild = NULL;

    if (2*i+1 <= n)
        root->rChild = create(2*i+1);
    else root->rChild = NULL;
    return root;
}

void pre_order(Node *root) { // 先序遍历
    if (root == NULL)
        return;
    printf("%d ", root->date);
    pre_order(root->lChild);
    pre_order(root->rChild);
}

void in_order(Node *root) { // 中序遍历
    if (root == NULL)
        return;
    in_order(root->lChild);
    printf("%d ", root->date);
    in_order(root->rChild);
}

void post_order(Node *root) { // 后序遍历
    if (root == NULL)
        return;
    post_order(root->lChild);
    post_order(root->rChild);
    printf("%d ", root->date);
}

int main() {
    while(cin >> n) {
        Node *root = create(1);

        pre_order(root);
        cout << endl;

        in_order(root);
        cout << endl;

        post_order(root);
        cout << endl;
    }
    return 0;
}