求一棵普通树的两个结点的最低公共祖先

1 #include <iostream>
2 #include <list>
3 #include <vector>
4 using namespace std;
5
6 struct TreeNode //节点
7 {
8     char m_nValue;
9     vector<TreeNode*> m_vChildren;
10 };
11
12 TreeNode* ConstructTree(TreeNode** pNode1 , TreeNode** pNode2)
13 {
14     TreeNode* A = new TreeNode();
15     A->m_nValue = 'A';
16     TreeNode* B = new TreeNode();
17     B->m_nValue = 'B';
18     TreeNode* C = new TreeNode();
19     C->m_nValue = 'C';
20     TreeNode* D = new TreeNode();
21     D->m_nValue = 'D';
22     TreeNode* E = new TreeNode();
23     E->m_nValue = 'E';
24     TreeNode* F = new TreeNode();
25     F->m_nValue = 'F';
26     TreeNode* G = new TreeNode();
27     G->m_nValue = 'G';
28     TreeNode* H = new TreeNode();
29     H->m_nValue = 'H';
30     TreeNode* I = new TreeNode();
31     I->m_nValue = 'I';
32     TreeNode* J = new TreeNode();
33     J->m_nValue = 'J';
34
35
36     A->m_vChildren.push_back(B);
37     A->m_vChildren.push_back(C);
38     B->m_vChildren.push_back(D);
39     B->m_vChildren.push_back(E);
40     D->m_vChildren.push_back(F);
41     D->m_vChildren.push_back(G);
42     E->m_vChildren.push_back(H);
43     E->m_vChildren.push_back(I);
44     E->m_vChildren.push_back(J);
45
46     *pNode1 = F;
47     *pNode2 = G;
48     return A;
49 }
50
51
52
53 bool GetNodePath(TreeNode* pRoot , TreeNode* pNode , list<TreeNode*>& path)
54 {
55     if (pRoot == pNode)
56     {
57         return true;
58     }
59     bool find = false ;
60     path.push_back(pRoot);
61     vector<TreeNode*>::iterator it = pRoot->m_vChildren.begin();
62     while (!find && it != pRoot->m_vChildren.end())
63     {
64         find = GetNodePath(*it ,pNode , path ) ;
65         it++ ;
66     }
67     if (!find)
68     {
69         path.pop_back();
70     }
71     return find;
72 }
73
74 TreeNode* GetLastCommonNode(list<TreeNode*>& path1 , list<TreeNode*>& path2 )
75 {
76     if (path1.empty() || path2.empty())
77     {
78         return NULL;
79     }
80     list<TreeNode*>::const_iterator it1 = path1.begin();
81     list<TreeNode*>::const_iterator it2 = path2.begin();
82     TreeNode* temp = NULL ;
83     while ( it1 != path1.end() && it2 != path2.end() && (*it1 == *it2))
84     {
85         temp = *it1 ;
86         it1++;
87         it2++;
88     }
89
90     return temp;
91 }
92
93 TreeNode* GetLastCommonParent(TreeNode* pRoot, TreeNode* pNode1, TreeNode* pNode2)
94 {
95     if (pRoot == NULL || pNode1 == NULL || pNode2 == NULL)
96     {
97         return NULL;
98     }
99     list<TreeNode*> path1 ;
100     GetNodePath(pRoot, pNode1, path1);
101
102     list<TreeNode*> path2 ;
103     GetNodePath(pRoot, pNode2, path2);
104
105     return GetLastCommonNode(path1, path2);
106 }
107
108
109
110 int main()
111 {
112     TreeNode *pNode1 = NULL , *pNode2 = NULL ;
113     TreeNode* pRoot = ConstructTree(&pNode1, &pNode2);
114     TreeNode* LastCommonParent = GetLastCommonParent(pRoot, pNode1, pNode2);
115
116     cout<<LastCommonParent->m_nValue<<endl;
117     getchar();
118     return 0;
119
120 }