stack using linked list

Spart-v6 · abranhe · commit a967b4521307 · 2020-10-08T08:59:15.000-04:00
diff --git a/algorithms/data-structures/stack/stack_using_linked_list.cpp b/algorithms/data-structures/stack/stack_using_linked_list.cpp
@@ -0,0 +1,107 @@
+#include<iostream>
+#include<cstdio>
+
+using namespace std;
+
+//- Global Variable (came from main)!
+struct Node *top = NULL; 
+
+struct Node{
+    int data;
+    struct Node *next; 
+};
+
+void linkedlistTraversal(struct Node * ptr){
+    while(ptr!=NULL){
+        printf("Element: %d\n", ptr->data);
+        ptr = ptr->next; 
+    }
+}
+
+int isEmpty(struct Node* top){
+    if(top == NULL){
+        return 1;
+    }
+    return 0;
+}
+
+int isFull(struct Node* top){
+    struct Node * n = (struct Node *) malloc(sizeof(struct Node)); 
+    if(n == NULL){ 
+        return 1;
+    }
+    return 0;
+}
+
+struct Node* push(struct Node* top, int data){
+    if(isFull(top)){
+        printf("Stack Overflow!\n");
+    }
+    else{
+        struct Node * n = (struct Node*) malloc(sizeof(struct Node)); 
+        n->data = data; 
+        n->next = top; 
+        top = n; 
+        return top;
+    }
+}
+
+int pop(struct Node * tp){
+    if(isEmpty(tp)){
+        printf("Stack Underflow!");
+    }
+    else{
+        struct Node * n = tp; 
+        top = (tp)->next; 
+        int x = n->data; 
+        free(n); 
+        return x;
+    }
+}
+
+int peek(int pos){     
+    struct Node * ptr = top;
+    for (int i = 0; (i < pos-1 && ptr!=NULL); i++)
+    {
+        ptr = ptr->next;
+    }
+    if(ptr!=NULL){
+        return ptr->data;
+    }
+    else{
+        return -1; // assuming there's no -ve element in stack 
+    }
+}
+
+int stackTop(struct Node * top){
+    return top->data;
+}
+
+int stackBottom(struct Node * top){
+    struct Node * p = top;
+    while(p->next!=NULL){
+        p = p->next;
+    }
+    return p->data;
+}
+
+int main()
+{
+    top = push(top, 69);
+    top = push(top, 10);
+    top = push(top, 8);
+    top = push(top, 7);
+    linkedlistTraversal(top);
+
+    for (int i = 1; i <= 4; i++)
+    {
+        printf("The element at position %d is %d\n",i,peek(i));  
+    }
+    
+    // printf("The top most element in stack is %d\n",stackTop(top));
+    printf("The bottom most element in stack is %d\n",stackBottom(top));
+
+    
+
+    return 0;
+}
