DStack impl

Author: prasath95

main.java

@@ -1,3 +1,5 @@
+import stack.Stack;
+
 /**
  * main
  */

stack/DStack.java

@@ -0,0 +1,54 @@
+package stack;
+
+public class DStack {
+
+    int capacity=2;
+    int[] stack = new int[capacity];
+    int top = 0;
+
+    public void push(int value) {
+        if(size()==capacity){
+            expand();
+        }
+
+        stack[top] = value;
+        top++;
+    }
+
+    private void expand() {
+        int length=size();
+        int newStack[]=new int[capacity*2];
+        System.arraycopy(stack, 0, newStack, 0, length);
+        stack=newStack;
+        capacity *=2;
+    }
+
+    public int pop() {
+        if (isEmpty()) {
+            System.out.println("stack is empty");
+            return -1;
+        } else {
+            top--;
+            int value = stack[top];
+            stack[top] = 0;
+            return value;
+        }
+
+    }
+
+    public int size() {
+        return top;
+    }
+
+    public boolean isEmpty() {
+        if (size() <= 0) {
+            return true;
+        }
+        return false;
+    }
+
+    public int peek() {
+        return stack[top - 1];
+    }
+
+}

Stack.java renamed to stack/Stack.java

@@ -1,3 +1,4 @@
+package stack;
 import java.util.ArrayList;
 
 public class Stack {
@@ -18,7 +19,6 @@ public void push(int value) {
             stackArray[top] = value;
             top++;
         }
-
     }
 
     public int pop() {