c语言之单链表的创建及排序
今天对之前学习过的链表知识进行简单的总结顺便写点代码；创建一个链表有头插法跟尾插法两种，在下面代码中我们为结点分配的内存实在堆上分配的，因此需要我们手动释放，释放用free（）函数
下面代码贴出具体代码：
1 #include <stdio.h> 2 #include <stdlib.h> 3 4 struct person { 5 int age; 6 struct person *next; 7 }; 8 9 struct person *insert_head(struct person *head, int age); 10 struct person *insert_tail(struct person *head, int age); 11 void destroy_list(struct person *head); 12 void show(struct person *head); 13 14 int main() 15 { 16 struct person *head = NULL; 17 head = insert_tail(head, 20); 18 head = insert_tail(head, 30); 19 head = insert_tail(head, 60); 20 head = insert_tail(head, 50); 21 head = insert_tail(head, 40); 22 show(head); 23 24 return 0； 25 } 26 27 /*头插法*/ 28 struct person *insert_head(struct person *head, int age) 29 { 30 struct person *tmp = NULL; 31 32 tmp = (struct person *)malloc(sizeof(struct person)); 33 tmp->age = age; 34 tmp->next = NULL; 35 36 if(NULL == head) { 37 return tmp; 38 } 39 tmp->next = head; 40 head = tmp; 41 42 return head; 43 } 44 45 /*尾插法*/ 46 struct person *insert_tail(struct person *head, int age) 47 { 48 struct person *tmp = NULL; 49 struct person *find = NULL; 50 51 tmp = (struct person *)malloc(sizeof(struct person)); 52 tmp->age = age; 53 tmp->next = NULL; 54 55 if(NULL == head) { 56 return tmp; 57 } 58 find = head; 59 while(find->next) { 60 find = find->next; 61 } 62 find->next = tmp; 63 64 return head; 65 } 66 67 /*销毁整个链表*/ 68 void destroy_list(struct person *head) 69 { 70 struct person *tmp = NULL; 71 72 tmp = head->next; 73 while(tmp) { 74 head->next = tmp->next; 75 free(tmp); 76 tmp = head->next; 77 } 78 } 79 80 /*遍历链表*/ 81 void show(struct person *head) 82 { 83 struct person *tmp = head; 84 while(tmp) { 85 printf("aeg is %d\n", tmp->age); 86 tmp = tmp->next; 87 } 88 } 89 90
上面的是创建了一个简单的链表，下面我们对链表进行简单的排序：
对于下面的链表排序：我们可以分为三步：
（1）在原链表中找到最小的
（2）从原链表摘下最小的
（3）一次插入到新链表
循环直到原链表为空
1 #include <stdio.h> 2 #include <stdlib.h> 3 4 struct person { 5 int age; 6 struct person *next; 7 }; 8 9 struct person *insert_head(struct person *head, int age); 10 struct person *insert_tail(struct person *head, int age); 11 struct person *insert_sort(struct person *head); 12 void destroy_list(struct person *head); 13 void show(struct person *head); 14 15 int main() 16 { 17 struct person *head = NULL; 18 head = insert_tail(head, 20); 19 head = insert_tail(head, 30); 20 head = insert_tail(head, 60); 21 head = insert_tail(head, 50); 22 head = insert_tail(head, 40); 23 show(head); 24 printf("------------------------------\n"); 25 head = insert_sort(head); 26 show(head); 27 } 28 29 /*头插法*/ 30 struct person *insert_head(struct person *head, int age) 31 { 32 struct person *tmp = NULL; 33 34 tmp = (struct person *)malloc(sizeof(struct person)); 35 tmp->age = age; 36 tmp->next = NULL; 37 38 if(NULL == head) { 39 return tmp; 40 } 41 tmp->next = head; 42 head = tmp; 43 44 return head; 45 } 46 47 /*尾插法*/ 48 struct person *insert_tail(struct person *head, int age) 49 { 50 struct person *tmp = NULL; 51 struct person *find = NULL; 52 53 tmp = (struct person *)malloc(sizeof(struct person)); 54 tmp->age = age; 55 tmp->next = NULL; 56 57 if(NULL == head) { 58 return tmp; 59 } 60 find = head; 61 while(find->next) { 62 find = find->next; 63 } 64 find->next = tmp; 65 66 return head; 67 } 68 69 /*销毁整个链表*/ 70 void destroy_list(struct person *head) 71 { 72 struct person *tmp = NULL; 73 74 tmp = head->next; 75 while(tmp) { 76 head->next = tmp->next; 77 free(tmp); 78 tmp = head->next; 79 } 80 } 81 82 #if 0 83 /*从大到小*/ 84 struct person *insert_sort(struct person *head) 85 { 86 struct person *tmp = NULL; 87 struct person *newhead = NULL; 88 struct person *min = NULL; 89 struct person *min_pre = NULL; 90 91 if(NULL == head || NULL == head->next) 92 return head; 93 94 while(head) { 95 tmp = head; 96 min = head; 97 min_pre = NULL; 98 99 /*step 1:find min*/ 100 while(tmp->next) { 101 if(min->age > tmp->next->age) { 102 min_pre = tmp; 103 min = tmp->next; 104 } 105 tmp = tmp->next; 106 } 107 108 /*step 2: cut min*/ 109 if(min == head) { 110 head = head->next; 111 min->next = NULL; 112 } 113 else { 114 min_pre->next = min->next; 115 min->next = NULL; 116 } 117 118 /*step 3: insert new list*/ 119 if(NULL == newhead) { 120 newhead = min; 121 continue; 122 } 123 min->next = newhead; 124 newhead = min; 125 } 126 127 return newhead; 128 } 129 130 #else 131 /*从小到大*/ 132 struct person *insert_sort(struct person *head) 133 { 134 struct person *tmp = NULL; 135 struct person *newhead = NULL; 136 struct person *newtail = NULL; 137 struct person *min = NULL; 138 struct person *min_pre = NULL; 139 140 if(NULL == head || NULL == head->next) 141 return head; 142 143 while(head) { 144 tmp = head; 145 min = head; 146 min_pre = NULL; 147 148 /*step 1: find min*/ 149 while(tmp->next) { 150 if(min->age > tmp->next->age) { 151 min_pre = tmp; 152 min = tmp->next; 153 } 154 tmp = tmp->next; 155 } 156 157 /*step 2: cut min*/ 158 if(min == head) { 159 head = head->next; 160 min->next = NULL; 161 } 162 else { 163 min_pre->next = min->next; 164 min->next = NULL; 165 } 166 167 /*step 3: insert new list*/ 168 if(NULL == newhead) { 169 newhead = min; 170 newtail = min; 171 continue; 172 } 173 newtail->next = min; 174 newtail = newtail->next; 175 } 176 177 return newhead; 178 } 179 #endif 180 181 /*遍历链表*/ 182 void show(struct person *head) 183 { 184 struct person *tmp = head; 185 while(tmp) { 186 printf("aeg is %d\n", tmp->age); 187 tmp = tmp->next; 188 } 189 }
