diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 839607f..ed51732 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -25,7 +25,8 @@
   "keyToString": {
     "RunOnceActivity.OpenProjectViewOnStart": "true",
     "RunOnceActivity.ShowReadmeOnStart": "true",
-    "last_opened_file_path": "C:/Users/39389/Documents/Repository/HackerJava"
+    "last_opened_file_path": "C:/Users/39389/Documents/Repository/HackerJava",
+    "settings.editor.selected.configurable": "preferences.pluginManager"
   }
 }]]></component>
   <component name="SpellCheckerSettings" RuntimeDictionaries="0" Folders="0" CustomDictionaries="0" DefaultDictionary="application-level" UseSingleDictionary="true" transferred="true" />
diff --git a/SeventhWave/1darray2.java b/SeventhWave/1darray2.java
new file mode 100644
index 0000000..d816820
--- /dev/null
+++ b/SeventhWave/1darray2.java
@@ -0,0 +1,61 @@
+import java.io.*;
+import java.util.*;
+import java.text.*;
+import java.math.*;
+import java.util.regex.*;
+
+public class Solution {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        int t = Integer.parseInt(scanner.nextLine());
+        for (int i = 0; i < t; i++) {
+            int n = scanner.nextInt();
+            int m = scanner.nextInt();
+            int[] arr = new int[n];
+            for (int j = 0; j < n; j++) {
+                arr[j] = scanner.nextInt();
+            }
+            solve(n, m, arr);
+        }
+    }
+
+    public static void solve(int n, int m, int[] arr) {
+        if (solve(n, m, arr, new boolean[n], 0)) {
+            System.out.println("YES");
+        } else {
+            System.out.println("NO");
+        }
+    }
+
+    public static boolean solve(int n, int m, int[] arr, boolean[] visited, int curr) {
+        if (curr + m >= n || curr + 1 == n) {
+            return true;
+        }
+
+        boolean[] newVisited = new boolean[n];
+        for (int i = 0; i < n; i++) {
+            newVisited[i] = visited[i];
+        }
+
+        boolean s = false;
+        if (!visited[curr + 1] && arr[curr + 1] == 0) {
+            newVisited[curr + 1] = true;
+            s = solve(n, m, arr, newVisited, curr + 1);
+        }
+        if (s) {
+            return true;
+        }
+        if (m > 1 && arr[curr + m] == 0 && !visited[curr + m]) {
+            newVisited[curr + m] = true;
+            s = solve(n, m, arr, newVisited, curr + m);
+        }
+        if (s) {
+            return true;
+        }
+        if (curr > 0 && arr[curr - 1] == 0 && !visited[curr - 1]) {
+            newVisited[curr - 1] = true;
+            s = solve(n, m, arr, newVisited, curr - 1);
+        }
+        return s;
+    }
+}
\ No newline at end of file
diff --git a/SeventhWave/arraylist.java b/SeventhWave/arraylist.java
new file mode 100644
index 0000000..016c7a4
--- /dev/null
+++ b/SeventhWave/arraylist.java
@@ -0,0 +1,40 @@
+import java.io.*;
+import java.util.*;
+import java.text.*;
+import java.math.*;
+import java.util.regex.*;
+
+public class Solution {
+
+    public static void main(String[] args) {
+        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
+        Scanner scan = new Scanner(System.in);
+
+        int total = scan.nextInt();
+
+        ArrayList<ArrayList<Integer>> mainlist = new ArrayList<>();
+
+        for (int i = 0; i < total; i++) {
+            int size = scan.nextInt();
+            ArrayList<Integer> list = new ArrayList();
+
+            for (int j = 0; j < size; j++) {
+                int item = scan.nextInt();
+                list.add(item);
+            }
+            mainlist.add(list);
+        }
+
+        int totalprint = scan.nextInt();
+        for (int k = 0; k < totalprint; k++) {
+            int row = scan.nextInt();
+            int col = scan.nextInt();
+            try {
+                System.out.println(mainlist.get(row - 1).get(col - 1));
+            } catch (Exception e) {
+                System.out.println("ERROR!");
+            }
+        }
+        scan.close();
+    }
+}
\ No newline at end of file
diff --git a/SeventhWave/dstructures.java b/SeventhWave/dstructures.java
new file mode 100644
index 0000000..b1e9867
--- /dev/null
+++ b/SeventhWave/dstructures.java
@@ -0,0 +1,36 @@
+import java.io.*;
+import java.util.*;
+import java.text.*;
+import java.math.*;
+import java.util.regex.*;
+
+public class Solution {
+
+    public static void main(String[] args) {
+        try {
+            int no_of_entries = 0;
+            int i = 0;
+            String name = null;
+            int number = 0;
+            String query = null;
+            HashMap<String, Integer> phoneBook = new HashMap<String, Integer>();
+            BufferedReader b = new BufferedReader(new InputStreamReader(
+                    System.in));
+            no_of_entries = Integer.parseInt(b.readLine());
+            while (i < no_of_entries) {
+                name = b.readLine();
+                number = Integer.parseInt(b.readLine());
+                phoneBook.put(name, number);
+                i++;
+            }
+            while (!(query = b.readLine().trim()).isEmpty()) {
+                if (phoneBook.containsKey(query))
+                    System.out.println(query + "=" + phoneBook.get(query));
+                else
+                    System.out.println("Not found");
+            }
+        } catch (Exception e) {
+
+        }
+    }
+}
\ No newline at end of file
diff --git a/SeventhWave/list.java b/SeventhWave/list.java
new file mode 100644
index 0000000..328a786
--- /dev/null
+++ b/SeventhWave/list.java
@@ -0,0 +1,38 @@
+import java.io.*;
+import java.util.*;
+import java.text.*;
+import java.math.*;
+import java.util.regex.*;
+
+public class Solution {
+
+    public static void main(String[] args) {
+        final Scanner in = new Scanner(System.in);
+        final int size = in.nextInt();
+        final List<Integer> list = new LinkedList<>();
+        for (int i = 0; i < size; i++) {
+            list.add(in.nextInt());
+        }
+        final int commandCount = in.nextInt();
+        for (int i = 0; i < commandCount; i++) {
+            in.nextLine();
+            String command = in.nextLine();
+            if (command.equals("Insert")) {
+                int index = in.nextInt();
+                int value = in.nextInt();
+                list.add(index, value);
+            } else {
+                int index = in.nextInt();
+                list.remove(index);
+            }
+        }
+        int count = 0;
+        for (Integer number : list) {
+            System.out.print(number);
+            if (count != list.size() - 1) {
+                System.out.print(" ");
+            }
+            count++;
+        }
+    }
+}
\ No newline at end of file
diff --git a/SeventhWave/stack.java b/SeventhWave/stack.java
new file mode 100644
index 0000000..670d6cc
--- /dev/null
+++ b/SeventhWave/stack.java
@@ -0,0 +1,39 @@
+import java.io.*;
+import java.util.*;
+import java.text.*;
+import java.math.*;
+import java.util.regex.*;
+
+public class Solution {
+
+    public static boolean isBalanced(String s) {
+        Stack<Character> stack = new Stack<Character>();
+        for (int i = 0; i < s.length(); ++i) {
+            if (s.charAt(i) == '(') stack.push('(');
+            else if (s.charAt(i) == '{') stack.push('{');
+            else if (s.charAt(i) == '[') stack.push('[');
+            else if (s.charAt(i) == ')') {
+                if (stack.isEmpty()) return false;
+                if (stack.pop() != '(') return false;
+            } else if (s.charAt(i) == '}') {
+                if (stack.isEmpty()) return false;
+                if (stack.pop() != '{') return false;
+            } else if (s.charAt(i) == ']') {
+                if (stack.isEmpty()) return false;
+                if (stack.pop() != '[') return false;
+            }
+        }
+        return stack.isEmpty();
+    }
+
+    public static void main(String[] args) {
+        Stack<Character> stack = new Stack<Character>();
+        Scanner sc = new Scanner(System.in);
+        String line;
+        while (sc.hasNextLine()) {
+            line = sc.nextLine();
+            if (isBalanced(line)) System.out.println("true");
+            else System.out.println("false");
+        }
+    }
+}
\ No newline at end of file