diff --git a/.gitignore b/.gitignore
index cf3452c5ed9711da7cb48b328277114d87435598..be4e21604f0029f5107fa5b6efaf8f36f0518239 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 gen-branch.js
+.DS_Store
 package.json
 package-lock.json
 node_modules
diff --git a/Main.java b/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..ac824ab88ca8cf50955cbbb491f124b630262f16
--- /dev/null
+++ b/Main.java
@@ -0,0 +1,28 @@
+class Main {
+  public static void main(String[] args) {
+    // Stack s = new Stack();
+    // System.out.println(s.isEmpty());
+    // try {
+    //     System.out.println(s.peek());
+    // } catch(Exception e){
+    //     e.printStackTrace();
+    // }
+    // s.push(10);
+    // s.push(20);
+    // s.push(30);
+    // try {
+    //   int v = s.pop();
+    //   System.out.println(v);
+    // } catch(Exception e){
+    //   e.printStackTrace();
+    // }
+    
+    // int sz = s.size();
+    // System.out.println(sz);
+
+    Maze maze = new Maze();
+    Tuple start = new Tuple(1,1);
+    maze.walk(start);
+
+  }
+}
\ No newline at end of file
diff --git a/Maze.java b/Maze.java
new file mode 100644
index 0000000000000000000000000000000000000000..5804842bc76b2a6917c3e615b2a5c94427c6d27a
--- /dev/null
+++ b/Maze.java
@@ -0,0 +1,114 @@
+public class Maze {
+  private boolean[][] maze= {
+      {false, false, false, false, false, false, false, false},
+      {false, true,  true,  true,  true,  true,  true,  false},
+      {false, true,  false, true,  false, false, false, false},
+      {false, false, false, true,  true,  true,  true,  false},
+      {false, true,  false, false, false, false, true,  false},
+      {false, true,  false, false, true,  false, true,  false},
+      {false, true,  true,  true,  true,  false, true,  false},
+      {false, false, false, false, false, false, false, false}
+    }; 
+  private Tuple end;
+  
+  Maze(){
+    
+    end = new Tuple(6,6);
+  }
+
+  public void walk(Tuple start){
+      // bad solution
+      boolean[][] isDiscovered = {
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false},
+      {false, false, false, false, false, false, false, false}
+    };
+
+    // TupleStack stack = new TupleStack();
+    Stack<Tuple> stack = new Stack<Tuple>();
+    try {
+      stack.push(start);
+    } catch(Exception e){
+      e.printStackTrace();
+    }
+    
+    isDiscovered[start.first][start.second] = true;
+
+    while(!stack.isEmpty()){
+      Tuple currentLocation = null;
+      try {
+        currentLocation = stack.pop();
+        if(currentLocation != null){
+          System.out.println(currentLocation.toString());
+        }
+      } catch(Exception e){
+        e.printStackTrace();
+      }      
+
+      // Termination case
+      if(currentLocation !=null && currentLocation.first == end.first && currentLocation.second == end.second){
+        // System.out.println(currentLocation.toString());
+        System.out.println("Reached");
+        break;
+      }
+
+      // North
+      if(currentLocation !=null && currentLocation.first>0){
+        if(maze[currentLocation.first-1][currentLocation.second] && !isDiscovered[currentLocation.first-1][currentLocation.second]){
+          Tuple temp = new Tuple(currentLocation.first-1, currentLocation.second);
+          try {
+              stack.push(temp);
+            } catch(Exception e){
+              e.printStackTrace();
+          }
+          isDiscovered[currentLocation.first-1][currentLocation.second] = true;
+        }
+      }
+      // West
+      if(currentLocation !=null && currentLocation.second>0){
+        if(maze[currentLocation.first][currentLocation.second-1] && !isDiscovered[currentLocation.first][currentLocation.second-1]){
+          Tuple temp = new Tuple(currentLocation.first, currentLocation.second-1);
+          try {
+              stack.push(temp);
+            } catch(Exception e){
+              e.printStackTrace();
+          }
+          isDiscovered[currentLocation.first][currentLocation.second-1] = true;
+        }
+      }
+      // South
+      if(currentLocation !=null && currentLocation.first<6){
+        if(maze[currentLocation.first+1][currentLocation.second] && !isDiscovered[currentLocation.first+1][currentLocation.second]){
+          Tuple temp = new Tuple(currentLocation.first+1, currentLocation.second);
+          try {
+              stack.push(temp);
+            } catch(Exception e){
+              e.printStackTrace();
+          }
+          isDiscovered[currentLocation.first+1][currentLocation.second] = true;
+        }
+      }
+      // East
+      if(currentLocation !=null && currentLocation.second<6){
+        if(maze[currentLocation.first][currentLocation.second+1] && !isDiscovered[currentLocation.first][currentLocation.second+1]){
+          Tuple temp = new Tuple(currentLocation.first, currentLocation.second+1);
+          try {
+              stack.push(temp);
+            } catch(Exception e){
+              e.printStackTrace();
+          }
+          isDiscovered[currentLocation.first][currentLocation.second+1] = true;
+        }
+      }
+    }
+
+    System.out.println("Finished");
+
+  }
+
+}
\ No newline at end of file
diff --git a/Stack.java b/Stack.java
new file mode 100644
index 0000000000000000000000000000000000000000..41d19dee026c37020f88a0cb148518307afafdab
--- /dev/null
+++ b/Stack.java
@@ -0,0 +1,43 @@
+public class Stack<T> {
+  private T[] stack;
+  private int top;
+  private static int SIZE = 100;
+
+  Stack(){
+    stack = (T[])new Object[SIZE];
+    top = 0;
+  }
+
+  public void push(T value){
+    if(top >= SIZE){
+      System.out.println("Stack overflow");
+      // throw new Exception("Stack Overflow");
+    }
+    stack[top] = value;
+    top++;
+  }
+
+  public T pop() throws Exception {
+    if(top <=0){
+      throw new Exception("Stack empty");
+    } 
+    top--;
+    return stack[top];
+  }
+
+  public T peek() throws Exception {
+    if(top <=0){
+      throw new Exception("Stack empty");
+    } else {
+       return stack[top-1];
+    }
+  }
+
+  public boolean isEmpty(){
+    return top == 0;
+  }
+
+  public int size(){
+    return top;
+  }
+}
\ No newline at end of file
diff --git a/Tuple.java b/Tuple.java
new file mode 100644
index 0000000000000000000000000000000000000000..52765c25aae296e021f76bdcfbe8dfaa1143f63f
--- /dev/null
+++ b/Tuple.java
@@ -0,0 +1,16 @@
+public class Tuple {
+
+    public  int first;
+
+    public  int second;
+
+    Tuple(int a, int b){
+        first = a;
+        second = b;
+    }
+
+    public String toString(){
+        return "(" + first + ", " + second + ")";
+    }
+
+}
\ No newline at end of file
diff --git "a/\350\257\276\344\273\266/lecture03-stack-queue.pdf" "b/\350\257\276\344\273\266/lecture03-stack-queue.pdf"
new file mode 100644
index 0000000000000000000000000000000000000000..08e8e4e5c3bb10c9fa74da7a70e257118b3b15cd
Binary files /dev/null and "b/\350\257\276\344\273\266/lecture03-stack-queue.pdf" differ