JZ-C-50
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剑指offer第五十题:树中两个结点的最低公共祖先:这里的树是普通树,且没有指向父结点的指针。
1 //============================================================================ 2 // Name : JZ-C-50.cpp 3 // Author : Laughing_Lz 4 // Version : 5 // Copyright : All Right Reserved 6 // Description : 树中两个结点的最低公共祖先:这里的树是普通树,且没有指向父结点的指针。 7 //============================================================================ 8 9 #include <iostream> 10 #include <stdio.h> 11 #include "Tree.h" 12 #include <list> 13 using namespace std; 14 15 using namespace std; 16 /** 17 * 获得从树的根结点到某结点的路径 18 */ 19 bool GetNodePath(TreeNode* pRoot, TreeNode* pNode, list<TreeNode*>& path) { 20 if (pRoot == pNode) 21 return true; 22 23 path.push_back(pRoot); 24 25 bool found = false; 26 27 vector<TreeNode*>::iterator i = pRoot->m_vChildren.begin(); //这里的树为普通树,甚至不是二叉树。所以这里按照前序遍历子树即可。 28 while (!found && i < pRoot->m_vChildren.end()) { 29 found = GetNodePath(*i, pNode, path); 30 ++i; 31 } 32 33 if (!found) 34 path.pop_back(); 35 36 return found; 37 } 38 /** 39 * 获得两条路径的最后一个公共结点。 40 */ 41 TreeNode* GetLastCommonNode(const list<TreeNode*>& path1, 42 const list<TreeNode*>& path2) { 43 list<TreeNode*>::const_iterator iterator1 = path1.begin(); 44 list<TreeNode*>::const_iterator iterator2 = path2.begin(); 45 46 TreeNode* pLast = NULL; 47 48 while (iterator1 != path1.end() && iterator2 != path2.end()) { 49 if (*iterator1 == *iterator2) 50 pLast = *iterator1; //遍历完两条路径,得到最后一个公共结点。 51 52 iterator1++; 53 iterator2++; 54 } 55 56 return pLast; 57 } 58 59 TreeNode* GetLastCommonParent(TreeNode* pRoot, TreeNode* pNode1, 60 TreeNode* pNode2) { 61 if (pRoot == NULL || pNode1 == NULL || pNode2 == NULL) 62 return NULL; 63 64 list<TreeNode*> path1; 65 GetNodePath(pRoot, pNode1, path1); 66 67 list<TreeNode*> path2; 68 GetNodePath(pRoot, pNode2, path2); 69 70 return GetLastCommonNode(path1, path2); 71 } 72 73 // ====================测试代码==================== 74 75 void Test(char* testName, TreeNode* pRoot, TreeNode* pNode1, TreeNode* pNode2, 76 TreeNode* pExpected) { 77 if (testName != NULL) 78 printf("%s begins: \n", testName); 79 80 TreeNode* pResult = GetLastCommonParent(pRoot, pNode1, pNode2); 81 82 if ((pExpected == NULL && pResult == NULL) 83 || (pExpected != NULL && pResult != NULL 84 && pResult->m_nValue == pExpected->m_nValue)) 85 printf("Passed.\n"); 86 else 87 printf("Failed.\n"); 88 } 89 90 // 形状普通的树 91 // 1 92 // / 93 // 2 3 94 // / 95 // 4 5 96 // / \ / | 97 // 6 7 8 9 10 98 void Test1() { 99 TreeNode* pNode1 = CreateTreeNode(1); 100 TreeNode* pNode2 = CreateTreeNode(2); 101 TreeNode* pNode3 = CreateTreeNode(3); 102 TreeNode* pNode4 = CreateTreeNode(4); 103 TreeNode* pNode5 = CreateTreeNode(5); 104 TreeNode* pNode6 = CreateTreeNode(6); 105 TreeNode* pNode7 = CreateTreeNode(7); 106 TreeNode* pNode8 = CreateTreeNode(8); 107 TreeNode* pNode9 = CreateTreeNode(9); 108 TreeNode* pNode10 = CreateTreeNode(10); 109 110 ConnectTreeNodes(pNode1, pNode2); 111 ConnectTreeNodes(pNode1, pNode3); 112 113 ConnectTreeNodes(pNode2, pNode4); 114 ConnectTreeNodes(pNode2, pNode5); 115 116 ConnectTreeNodes(pNode4, pNode6); 117 ConnectTreeNodes(pNode4, pNode7); 118 119 ConnectTreeNodes(pNode5, pNode8); 120 ConnectTreeNodes(pNode5, pNode9); 121 ConnectTreeNodes(pNode5, pNode10); 122 123 Test("Test1", pNode1, pNode6, pNode8, pNode2); 124 } 125 126 // 树退化成一个链表 127 // 1 128 // / 129 // 2 130 // / 131 // 3 132 // / 133 // 4 134 // / 135 // 5 136 void Test2() { 137 TreeNode* pNode1 = CreateTreeNode(1); 138 TreeNode* pNode2 = CreateTreeNode(2); 139 TreeNode* pNode3 = CreateTreeNode(3); 140 TreeNode* pNode4 = CreateTreeNode(4); 141 TreeNode* pNode5 = CreateTreeNode(5); 142 143 ConnectTreeNodes(pNode1, pNode2); 144 ConnectTreeNodes(pNode2, pNode3); 145 ConnectTreeNodes(pNode3, pNode4); 146 ConnectTreeNodes(pNode4, pNode5); 147 148 Test("Test2", pNode1, pNode5, pNode4, pNode3); 149 } 150 151 // 树退化成一个链表,一个结点不在树中 152 // 1 153 // / 154 // 2 155 // / 156 // 3 157 // / 158 // 4 159 // / 160 // 5 161 void Test3() { 162 TreeNode* pNode1 = CreateTreeNode(1); 163 TreeNode* pNode2 = CreateTreeNode(2); 164 TreeNode* pNode3 = CreateTreeNode(3); 165 TreeNode* pNode4 = CreateTreeNode(4); 166 TreeNode* pNode5 = CreateTreeNode(5); 167 168 ConnectTreeNodes(pNode1, pNode2); 169 ConnectTreeNodes(pNode2, pNode3); 170 ConnectTreeNodes(pNode3, pNode4); 171 ConnectTreeNodes(pNode4, pNode5); 172 173 TreeNode* pNode6 = CreateTreeNode(6); 174 175 Test("Test3", pNode1, pNode5, pNode6, NULL); 176 } 177 178 // 输入NULL 179 void Test4() { 180 Test("Test4", NULL, NULL, NULL, NULL); 181 } 182 183 int main(int argc, char** argv) { 184 Test1(); 185 Test2(); 186 Test3(); 187 Test4(); 188 189 return 0; 190 }
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