1102. Invert a Binary Tree (25)

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本文介绍了一种翻转二叉树的算法实现，并通过具体的输入输出样例展示了如何使用该算法。文章提供了完整的C++代码，实现了二叉树的创建、层级遍历和中序遍历等功能。

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1102. Invert a Binary Tree (25)
时间限制 400 ms 内存限制 65536 kB 代码长度限制 16000 B
判题程序 Standard 作者 CHEN, Yue

The following is from Max Howell @twitter:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.
Now it’s your turn to prove that YOU CAN invert a binary tree!
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (<=10) which is the total number of nodes in the tree – and hence the nodes are numbered from 0 to N-1. Then N lines follow, each corresponds to a node from 0 to N-1, and gives the indices of the left and right children of the node. If the child does not exist, a “-” will be put at the position. Any pair of children are separated by a space.
Output Specification:
For each test case, print in the first line the level-order, and then in the second line the in-order traversal sequences of the inverted tree. There must be exactly one space between any adjacent numbers, and no extra space at the end of the line.
Sample Input:
8
1 -
- -
0 -
2 7
- -
- -
5 -
4 6
Sample Output:
3 7 2 6 4 0 5 1
6 5 7 4 3 2 0 1

#define _CRT_SECURE_NO_WARNINGS
#include <algorithm>
#include <iostream>
#include <string>
#include <vector> 
#include <queue>
#include <sstream>
#include <memory.h>

using namespace std;
const int MaxN = 12;
int Num[MaxN],N,P = 0,L = 0;
bool isRoot[MaxN];

typedef struct tnode
{
    int data;
    struct tnode * lchild;
    struct tnode * rchild;
}TNode;
TNode *Ptr[MaxN];


void Level(TNode * root)
{
    if (!root) return;

    queue<TNode *>que; que.push(root);
    while (que.size())
    {
        TNode * node = que.front(); que.pop();
        ++L;
        cout << node->data;
        if (L != N)
            cout << " ";

        if (node->rchild) que.push(node->rchild);
        if (node->lchild) que.push(node->lchild);
    }

}


void InOrder(TNode * root)
{
    if (!root)return;

    InOrder(root->rchild);

    cout << root->data; ++P;
    if (P != N)
        cout << " ";

    InOrder(root->lchild);

    delete root;
}

TNode * CreateTree(int N)
{
    for (int i = 0; i < N; ++i)
    {
        Ptr[i] = new TNode;
        Ptr[i]->data = i;
        Ptr[i]->lchild = Ptr[i]->rchild = NULL;
    }

    stringstream ss; string str;
    for (int i = 0; i < N; ++i)
    {
        getline(cin, str);
        ss << str;
        int k = 0;
        if (str[k] == '-')
        {
            Ptr[i]->lchild = NULL;
            ss.get();
            ss.get();
        }
        else
        {
            int lidx;
            ss >> lidx;
            Ptr[i]->lchild = Ptr[lidx];
            isRoot[lidx] = false;
        }

        while (str[k] != ' ')
            ++k;

        if (str[k+1] == '-')
        {
            Ptr[i]->rchild = NULL;
        }
        else
        {
            int ridx;
            ss >> ridx;
            Ptr[i]->rchild = Ptr[ridx];
            isRoot[ridx] = false;
        }

        ss.clear();
        ss.str("");

    }

    TNode * root = NULL;
    for (int i = 0; i < N; ++i)
    {
        if (isRoot[i])
        {
            root = Ptr[i];
            break;
        }
    }
    return root;
}
int main()
{
#ifdef _DEBUG
    freopen("data.txt", "r+", stdin);
#endif

    std::ios::sync_with_stdio(false);

    memset(isRoot, 1, sizeof(isRoot));
    cin >> N; cin.get();

    TNode * root = CreateTree(N);

    Level(root); cout << endl;
    InOrder(root);


    return 0;
}