面试题50—树中两个节点的最低公共祖先

示例代码：
头文件：tree.h

#include<iostream>#include<vector>using namespace std;struct TreeNode{    char value;    vector<TreeNode*> next;};TreeNode* CreateTreeNode(char data, int n);void ConnectTreeNode(TreeNode *parent, TreeNode *child, int n);void PrintTree(TreeNode *pRoot);void DestroyTree(TreeNode* pRoot);

源文件：tree.cpp

#include"tree.h"TreeNode* CreateTreeNode(char data,int n){    TreeNode *pRoot = new TreeNode();    pRoot->value = data;    pRoot->next = vector<TreeNode*>(n, NULL);    return pRoot;}void ConnectTreeNode(TreeNode *parent, TreeNode *child, int n){    if (parent != NULL)    {        parent->next[n-1] = child;    }}void PrintTree(TreeNode *pRoot){    if (pRoot)    {        cout << pRoot->value << endl;        for (int i = 0; i < pRoot->next.size(); i++)        {            if (pRoot->next[i])            {                cout << pRoot->value << "第" << i + 1 << "个结点:" << pRoot->next[i]->value << endl;            }        }        if (pRoot->next.size() == 0)        {            cout << pRoot->value << "没有子结点！"<< endl;        }        cout << endl;        //        for (int i = 0; i < pRoot->next.size(); i++)        {            PrintTree(pRoot->next[i]);        }    }}void DestroyTree(TreeNode* pRoot){    if (pRoot != NULL)    {        vector<TreeNode*> temp = pRoot->next;        delete pRoot;        for (int i = 0; i < temp.size(); i++)            DestroyTree(temp[i]);        pRoot = NULL;    }}

主函数：main.cpp

//面试题50—树中两个节点的最低公共祖先//示例代码：#include<iostream>#include"tree.h"using namespace std;bool CommonParentNode(TreeNode *pRoot, TreeNode* node,vector<TreeNode*>&path){    if (pRoot == node)        return true;    path.push_back(pRoot);    bool found = false;    int i = 0;    int n = pRoot->next.size();    while (!found&&i < n)    {        found = CommonParentNode(pRoot->next[i], node, path);        i++;    }    if (!found)        path.pop_back();    return found;}TreeNode* CommonParentNode(vector<TreeNode*>path1, vector<TreeNode*>path2){    int i = 0;    int n1 = path1.size();    int n2 = path2.size();    while (i < n1&&i < n2)    {        if (path1[i] == path2[i])            i++;        else            break;    }    if (i == 0)    {        return NULL;    }    else    {        return path1[i - 1];    }}int main(){    TreeNode *p1 = CreateTreeNode('A', 2);    TreeNode *p2 = CreateTreeNode('B', 2);    TreeNode *p3 = CreateTreeNode('C', 0);    TreeNode *p4 = CreateTreeNode('D', 2);    TreeNode *p5 = CreateTreeNode('E', 3);    TreeNode *p6 = CreateTreeNode('F', 0);    TreeNode *p7 = CreateTreeNode('G', 0);    TreeNode *p8 = CreateTreeNode('H', 0);    TreeNode *p9 = CreateTreeNode('I', 0);    TreeNode *p10 = CreateTreeNode('J', 0);    //    ConnectTreeNode(p1, p2, 1);    ConnectTreeNode(p1, p3, 2);    ConnectTreeNode(p2, p4, 1);    ConnectTreeNode(p2, p5, 2);    ConnectTreeNode(p4, p6, 1);    ConnectTreeNode(p4, p7, 2);    ConnectTreeNode(p5, p8, 1);    ConnectTreeNode(p5, p9, 2);    ConnectTreeNode(p5, p10, 3);    //===    //PrintTree(p1);    //===    vector<TreeNode*> path1;    vector<TreeNode*>path2;    bool found1 = CommonParentNode(p1, p4, path1);    bool found2 = CommonParentNode(p1, p5, path2);    for (int i = 0; i < path1.size(); i++)        cout << path1[i]->value << "";    if (found1&&found2)    {        TreeNode *res = CommonParentNode(path1, path2);        if (res)            cout << "最低共同祖先结点：" << res->value << endl;        else            cout << "没有共同祖先结点！" << endl;    }    DestroyTree(p1);}