剑指offer第十五题：链表中倒数第K个结点
1 //============================================================================ 2 // Name : JZ-C-15.cpp 3 // Author : Laughing_Lz 4 // Version : 5 // Copyright : All Right Reserved 6 // Description : 链表中倒数第K个结点 7 //============================================================================ 8 9 #include <iostream> 10 #include "List.h" 11 #include <stdio.h> 12 using namespace std; 13 14 ListNode* FindKthToTail(ListNode* node, unsigned int k) { 15 if (k == 0 || node == NULL) { 16 return NULL; 17 } 18 ListNode* head = node; 19 ListNode* follow = node; 20 for (unsigned int i = 0; i < k - 1; i++) { 21 if (head->m_pNext == NULL) { 22 return NULL; 23 } else { 24 head = head->m_pNext; 25 } 26 } 27 while (head->m_pNext != NULL) { 28 head = head->m_pNext; 29 follow = follow->m_pNext; 30 } 31 return follow; 32 } 33 34 // ====================测试代码==================== 35 // 测试要找的结点在链表中间 36 void Test1() { 37 printf("=====Test1 starts:===== "); 38 ListNode* pNode1 = CreateListNode(1); 39 ListNode* pNode2 = CreateListNode(2); 40 ListNode* pNode3 = CreateListNode(3); 41 ListNode* pNode4 = CreateListNode(4); 42 ListNode* pNode5 = CreateListNode(5); 43 44 ConnectListNodes(pNode1, pNode2); 45 ConnectListNodes(pNode2, pNode3); 46 ConnectListNodes(pNode3, pNode4); 47 ConnectListNodes(pNode4, pNode5); 48 49 printf("expected result: 4. "); 50 ListNode* pNode = FindKthToTail(pNode1, 2); 51 PrintListNode(pNode); 52 53 DestroyList(pNode1); 54 } 55 56 // 测试要找的结点是链表的尾结点 57 void Test2() { 58 printf("=====Test2 starts:===== "); 59 ListNode* pNode1 = CreateListNode(1); 60 ListNode* pNode2 = CreateListNode(2); 61 ListNode* pNode3 = CreateListNode(3); 62 ListNode* pNode4 = CreateListNode(4); 63 ListNode* pNode5 = CreateListNode(5); 64 65 ConnectListNodes(pNode1, pNode2); 66 ConnectListNodes(pNode2, pNode3); 67 ConnectListNodes(pNode3, pNode4); 68 ConnectListNodes(pNode4, pNode5); 69 70 printf("expected result: 5. "); 71 ListNode* pNode = FindKthToTail(pNode1, 1); 72 PrintListNode(pNode); 73 74 DestroyList(pNode1); 75 } 76 77 // 测试要找的结点是链表的头结点 78 void Test3() { 79 printf("=====Test3 starts:===== "); 80 ListNode* pNode1 = CreateListNode(1); 81 ListNode* pNode2 = CreateListNode(2); 82 ListNode* pNode3 = CreateListNode(3); 83 ListNode* pNode4 = CreateListNode(4); 84 ListNode* pNode5 = CreateListNode(5); 85 86 ConnectListNodes(pNode1, pNode2); 87 ConnectListNodes(pNode2, pNode3); 88 ConnectListNodes(pNode3, pNode4); 89 ConnectListNodes(pNode4, pNode5); 90 91 printf("expected result: 1. "); 92 ListNode* pNode = FindKthToTail(pNode1, 5); 93 PrintListNode(pNode); 94 95 DestroyList(pNode1); 96 } 97 98 // 测试空链表 99 void Test4() { 100 printf("=====Test4 starts:===== "); 101 printf("expected result: NULL. "); 102 ListNode* pNode = FindKthToTail(NULL, 100); 103 PrintListNode(pNode); 104 } 105 106 // 测试输入的第二个参数大于链表的结点总数 107 void Test5() { 108 printf("=====Test5 starts:===== "); 109 ListNode* pNode1 = CreateListNode(1); 110 ListNode* pNode2 = CreateListNode(2); 111 ListNode* pNode3 = CreateListNode(3); 112 ListNode* pNode4 = CreateListNode(4); 113 ListNode* pNode5 = CreateListNode(5); 114 115 ConnectListNodes(pNode1, pNode2); 116 ConnectListNodes(pNode2, pNode3); 117 ConnectListNodes(pNode3, pNode4); 118 ConnectListNodes(pNode4, pNode5); 119 120 printf("expected result: NULL. "); 121 ListNode* pNode = FindKthToTail(pNode1, 6); 122 PrintListNode(pNode); 123 124 DestroyList(pNode1); 125 } 126 127 // 测试输入的第二个参数为0 128 void Test6() { 129 printf("=====Test6 starts:===== "); 130 ListNode* pNode1 = CreateListNode(1); 131 ListNode* pNode2 = CreateListNode(2); 132 ListNode* pNode3 = CreateListNode(3); 133 ListNode* pNode4 = CreateListNode(4); 134 ListNode* pNode5 = CreateListNode(5); 135 136 ConnectListNodes(pNode1, pNode2); 137 ConnectListNodes(pNode2, pNode3); 138 ConnectListNodes(pNode3, pNode4); 139 ConnectListNodes(pNode4, pNode5); 140 141 printf("expected result: NULL. "); 142 ListNode* pNode = FindKthToTail(pNode1, 0); 143 PrintListNode(pNode); 144 145 DestroyList(pNode1); 146 } 147 148 int main(int argc, char** argv) { 149 Test1(); 150 Test2(); 151 Test3(); 152 Test4(); 153 Test5(); 154 Test6(); 155 156 return 0; 157 }