Merge pull request #548 from bdzyq/master

【707_设计链表】增加C实现

problems/0707.设计链表.md

@@ -154,7 +154,129 @@ private:
 
 
 ## 其他语言版本
+C:
+```C
+typedef struct {
+    int val;
+    struct MyLinkedList* next;
+}MyLinkedList;
 
+/** Initialize your data structure here. */
+
+MyLinkedList* myLinkedListCreate() {
+    //这个题必须用虚拟头指针,参数都是一级指针,头节点确定后没法改指向了!!!
+    MyLinkedList* head = (MyLinkedList *)malloc(sizeof (MyLinkedList));
+    head->next = NULL;
+    return head;
+}
+
+/** Get the value of the index-th node in the linked list. If the index is invalid, return -1. */
+int myLinkedListGet(MyLinkedList* obj, int index) {
+    MyLinkedList *cur = obj->next;
+    for (int i = 0; cur != NULL; i++){
+        if (i == index){
+            return cur->val;
+        }
+        else{
+            cur = cur->next;
+        }
+    }
+    return -1;
+}
+
+/** 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. */
+void myLinkedListAddAtHead(MyLinkedList* obj, int val) {
+    MyLinkedList *nhead = (MyLinkedList *)malloc(sizeof (MyLinkedList));
+    nhead->val = val;
+    nhead->next = obj->next;
+    obj->next = nhead;
+
+}
+
+/** Append a node of value val to the last element of the linked list. */
+void myLinkedListAddAtTail(MyLinkedList* obj, int val) {
+    MyLinkedList *cur = obj;
+    while(cur->next != NULL){
+        cur = cur->next;
+    }
+    MyLinkedList *ntail = (MyLinkedList *)malloc(sizeof (MyLinkedList));
+    ntail->val = val;
+    ntail->next = NULL;
+    cur->next = ntail;
+}
+
+/** 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. */
+void myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val) {
+    if (index == 0){
+        myLinkedListAddAtHead(obj, val);
+        return;
+    }
+    MyLinkedList *cur = obj->next;
+    for (int i = 1 ;cur != NULL; i++){
+        if (i == index){
+            MyLinkedList* newnode = (MyLinkedList *)malloc(sizeof (MyLinkedList));
+            newnode->val = val;
+            newnode->next = cur->next;
+            cur->next = newnode;
+            return;
+        }
+        else{
+            cur = cur->next;
+        }
+    }
+}
+
+/** Delete the index-th node in the linked list, if the index is valid. */
+void myLinkedListDeleteAtIndex(MyLinkedList* obj, int index) {
+    if (index == 0){
+        MyLinkedList *tmp = obj->next;
+        if (tmp != NULL){
+            obj->next = tmp->next;
+            free(tmp)     
+        }
+        return;
+    }
+    MyLinkedList *cur = obj->next;
+    for (int i = 1 ;cur != NULL && cur->next != NULL; i++){
+        if (i == index){
+            MyLinkedList *tmp = cur->next;
+            if (tmp != NULL) {
+                cur->next = tmp->next;
+                free(tmp);
+            }
+            return;
+        }
+        else{
+            cur = cur->next;
+        }
+    }
+    
+}
+
+void myLinkedListFree(MyLinkedList* obj) {
+    while(obj != NULL){
+        MyLinkedList *tmp = obj;
+        obj = obj->next;
+        free(tmp);
+    }
+}
+
+/**
+ * Your MyLinkedList struct will be instantiated and called as such:
+ * MyLinkedList* obj = myLinkedListCreate();
+ * int param_1 = myLinkedListGet(obj, index);
+ 
+ * myLinkedListAddAtHead(obj, val);
+ 
+ * myLinkedListAddAtTail(obj, val);
+ 
+ * myLinkedListAddAtIndex(obj, index, val);
+ 
+ * myLinkedListDeleteAtIndex(obj, index);
+ 
+ * myLinkedListFree(obj);
+*/
+```
 
 Java：
 ```Java