feat(codes/c): update linkedlist_stack.c some code

codes/c/chapter_stack_and_queue/linkedlist_stack.c

@@ -6,74 +6,87 @@
 
 #include "../include/include.h"
 
+/* 基于链表实现的栈 */
 struct LinkedListStack {
-    ListNode* stkTop;
-    size_t stkSize;
+    ListNode* stackTop; // 将头结点作为栈顶
+    size_t stkSize;     // 栈的长度
 };
 
 typedef struct LinkedListStack LinkedListStack;
 
-void new(LinkedListStack* stk) {
-    // 创建头结点
-    stk->stkTop = (ListNode *)malloc(sizeof(ListNode));
-    stk->stkTop->next = NULL;
-    stk->stkTop->val = 0;
-
-    // 初始化栈大小
+void constructor(LinkedListStack* stk) {
+    stk->stackTop = NULL;
     stk->stkSize = 0;
 }
-
+/* 获取栈的长度 */
 size_t size(LinkedListStack* stk) {
     assert(stk);
     return stk->stkSize;
 }
-
+/* 判断栈是否为空 */
 bool empty(LinkedListStack* stk) {
     assert(stk);
     return size(stk) == 0;
 }
-
-void push(LinkedListStack* stk, int num) {
-    assert(stk);
-
-    // 创建一个新结点
-    ListNode *n = (ListNode *)malloc(sizeof(ListNode));
-    ListNode *h;
-    n->next = NULL;
-    n->val = num;
-
-    // 遍历链表，将新结点挂在最后面
-    h = stk->stkTop;
-    while(h && h->next) {
-         h = h->next;
-    }
-    h->next = n;
-
-    // 栈大小自增
-    stk->stkSize++;
-}
-
-void pop(LinkedListStack* stk) {
-    assert(stk);
-    ListNode *h = stk->stkTop;
-    ListNode *n;
-    // 找到倒数第一个结点 h -> (h->next) -> (h->next->next)
-    while(h && h->next && h->next->next) {
-         h = h->next;
-    }
-
-    // 先保存倒数个结点，断开
-    n = h->next;
-    h->next = NULL;
-
-    // 删除保存的结点
-    free(n);
-}
-
+/* 访问栈顶元素 */
 int top(LinkedListStack* stk) {
     assert(stk);
+    if (size(stk) == 0 ) 
+        // 抛出异常
+    return stk->stackTop->val;
+}
+/* 入栈 */
+void push(LinkedListStack* stk, int num) {
+    assert(stk);
+    ListNode *node = (ListNode *)malloc(sizeof(ListNode));
+    node->next = stk->stackTop;
+    node->val = num;
+    stk->stackTop = node;
+    stk->stkSize++;
+}
+/* 出栈 */
+void pop(LinkedListStack* stk) {
+    assert(stk);
+    int num = top(stk);
+    ListNode *tmp = stk->stackTop;
+    stk->stackTop = stk->stackTop->next;
+    // 释放内存
+    free(tmp);
+    stk->stkSize--;
 }
 
+
+/* Driver Code */
 int main() {
+    /* 初始化栈 */
+    LinkedListStack stack;
+
+    /* 元素入栈 */
+    push(&stack, 1);
+    push(&stack, 3);
+    push(&stack, 2);
+    push(&stack, 5);
+    push(&stack, 4);
+
+    printf("栈 stack = ");
+    printStack(&stack);
+
+    /* 访问栈顶元素 */
+    int stackTop = top(&stack);
+    printf("栈顶元素 top = %d\r\n", stackTop);
+
+    /* 元素出栈 */
+    pop(&stack);
+    printf("出栈元素 pop = %d, 出栈后 stack =  ", stackTop);
+    printStack(&stack);
+
+    /* 获取栈的长度 */
+    size_t stackSize = size(&stack);
+    printf("栈的长度 size = %ld\r\n", stackSize);
+
+    /* 判断是否为空 */
+    bool isEmpty = empty(&stack);
+    printf("栈是否为空 = %d", isEmpty);
+
     return 0;
 }

codes/c/include/print_util.h

@@ -127,6 +127,14 @@ static void printTree(TreeNode *root) {
     printTreeHelper(root, NULL, false);
 }
 
+/**
+ * @brief Print a stack
+ *
+ * @param head
+ */
+static void printStack(void *stack) {
+    
+}
 
 #ifdef __cplusplus
 }