链表的常用操作
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <stdbool.h> 4 5 typedef struct { 6 int val; 7 struct MyLinkedList *next; 8 } MyLinkedList; 9 10 /** Initialize your data structure here. */ 11 12 MyLinkedList* myLinkedListCreate() { 13 MyLinkedList *result = (MyLinkedList *)malloc(sizeof(MyLinkedList)); 14 result->val = 0; 15 result->next = NULL; 16 return result; 17 } 18 19 /** Get the value of the index-th node in the linked list. If the index is invalid, return -1. */ 20 int myLinkedListGet(MyLinkedList* obj, int index) { 21 if (index < 0 || index >= obj->val) { 22 return -1; 23 } 24 25 while (index >= 0) { 26 obj = obj->next; 27 index--; 28 } 29 30 return obj->val; 31 } 32 33 /** Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list. */ 34 void myLinkedListAddAtHead(MyLinkedList* obj, int val) { 35 if (obj == NULL) { 36 return; 37 } 38 39 obj->val++; 40 MyLinkedList *temp = (MyLinkedList*)malloc(sizeof(MyLinkedList)); 41 temp->val = val; 42 temp->next = obj->next; 43 obj->next = temp; 44 } 45 46 /** Append a node of value val to the last element of the linked list. */ 47 void myLinkedListAddAtTail(MyLinkedList* obj, int val) { 48 if (obj == NULL) { 49 return; 50 } 51 52 obj->val++; 53 MyLinkedList *temp = (MyLinkedList*)malloc(sizeof(MyLinkedList)); 54 temp->next = NULL; 55 temp->val = val; 56 57 while (obj->next != NULL) { 58 obj = obj->next; 59 } 60 61 obj->next = temp; 62 } 63 64 /** Add a node of value val before the index-th node in the linked list. If index equals to the length of linked list, the node will be appended to the end of linked list. If index is greater than the length, the node will not be inserted. */ 65 void myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val) { 66 if (obj == NULL || index < 0 || index > obj->val) { 67 return; 68 } 69 70 if (index == obj->val) { 71 myLinkedListAddAtTail(obj, val); 72 return; 73 } 74 75 obj->val++; 76 MyLinkedList *temp = (MyLinkedList*)malloc(sizeof(MyLinkedList)); 77 temp->val = val; 78 temp->next = NULL; 79 80 while (index > 0) { 81 obj = obj->next; 82 index--; 83 } 84 85 temp->next = obj->next; 86 obj->next = temp; 87 } 88 89 /** Delete the index-th node in the linked list, if the index is valid. */ 90 void myLinkedListDeleteAtIndex(MyLinkedList* obj, int index) { 91 if (obj == NULL || obj->val == 0 || index < 0 || index + 1 > obj->val) { 92 return; 93 } 94 95 obj->val--; 96 while (index > 0) { 97 obj = obj->next; 98 index--; 99 } 100 101 MyLinkedList *temp = obj->next; 102 obj->next = temp->next; 103 free(temp); 104 } 105 106 void myLinkedListFree(MyLinkedList* obj) { 107 if (obj->next == NULL) { 108 free(obj); 109 return; 110 } 111 112 myLinkedListFree(obj->next); 113 obj->next = NULL; 114 myLinkedListFree(obj); 115 } 116 117 /** 118 * Your MyLinkedList struct will be instantiated and called as such: 119 * MyLinkedList* obj = myLinkedListCreate(); 120 * int param_1 = myLinkedListGet(obj, index); 121 122 * myLinkedListAddAtHead(obj, val); 123 124 * myLinkedListAddAtTail(obj, val); 125 126 * myLinkedListAddAtIndex(obj, index, val); 127 128 * myLinkedListDeleteAtIndex(obj, index); 129 130 * myLinkedListFree(obj); 131 */ 132 133 void show(MyLinkedList *obj) 134 { 135 while (obj != NULL) { 136 printf("%d ", obj->val); 137 obj = obj->next; 138 } 139 printf("\n"); 140 } 141 142 int main() 143 { 144 MyLinkedList *obj = NULL; 145 obj = myLinkedListCreate(); 146 myLinkedListAddAtHead(obj, 1); 147 show(obj); 148 myLinkedListAddAtTail(obj, 2); 149 show(obj); 150 myLinkedListAddAtIndex(obj, 0, 3); 151 show(obj); 152 myLinkedListAddAtIndex(obj, 2, 4); 153 show(obj); 154 myLinkedListDeleteAtIndex(obj, 0); 155 show(obj); 156 myLinkedListDeleteAtIndex(obj, 2); 157 show(obj); 158 // myLinkedListFree(obj); 159 160 return 0; 161 }
题目来源：LeetCode707
