diff --git a/December 01/question1.txt b/December 01/question1.txt
new file mode 100644
index 0000000..8cb9c75
--- /dev/null
+++ b/December 01/question1.txt	
@@ -0,0 +1,17 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int[] arr=new int[n-1];
+        int sum=0;
+        for(int i=0;i<n-1;i++)
+        {
+            arr[i]=s.nextInt();
+            sum+=arr[i];
+        }
+        int total=n*(n+1)/2;
+        int result=Math.abs(total-sum);
+        System.out.print(result);
+    }
+}
diff --git a/December 02/question2.txt b/December 02/question2.txt
new file mode 100644
index 0000000..fe6c47b
--- /dev/null
+++ b/December 02/question2.txt	
@@ -0,0 +1,36 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int[] arr=new int[n];
+        for(int i=0;i<n;i++)
+        {
+            arr[i]=s.nextInt();
+        }
+        solution(arr);
+    }
+    public static void solution(int[] arr)
+    {
+        int t;
+        for(int i=0;i<arr.length-1;i++)
+        {
+            if(i%2==0&&arr[i]>arr[i+1]){
+                   t=arr[i];
+                  arr[i]=arr[i+1];
+                  arr[i+1]=t;
+            }
+            
+            if(i%2!=0&&arr[i]<arr[i+1])
+            {
+                t=arr[i];
+                arr[i]=arr[i+1];
+                arr[i+1]=t;
+            }
+        }
+        for(int i=0;i<arr.length;i++)
+        {
+            System.out.println(arr[i]);
+        }
+    }
+}
diff --git a/December 03/question3.txt b/December 03/question3.txt
new file mode 100644
index 0000000..4134591
--- /dev/null
+++ b/December 03/question3.txt	
@@ -0,0 +1,43 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n1=s.nextInt();
+        int n2=s.nextInt();
+        System.out.println(solution(n1, n2));
+    }
+    public static String solution(int n1,int n2)
+    {
+        StringBuilder s=new StringBuilder();
+        if(Math.abs(n1-n2)>1)
+        return "not possible";
+        else
+        {
+            if(n1>=n2)
+            {
+            for(int i=0;i<n1+n2;i++)
+            {
+                if(i%2==0)
+                {
+                    s.insert(i,"R");
+                }
+                else
+                s.insert(i,"B");
+            }
+           }
+           else
+           {
+            for(int i=0;i<n1+n2;i++)
+            {
+                if(i%2==0)
+                {
+                    s.insert(i,"B");
+                }
+                else
+                s.insert(i,"R");
+                }
+            }
+        }
+        return s.toString();
+        }
+    }
diff --git a/December 04/question4.txt b/December 04/question4.txt
new file mode 100644
index 0000000..9b2a32e
--- /dev/null
+++ b/December 04/question4.txt	
@@ -0,0 +1,20 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int a=1;
+        int c;
+        int b=1;
+        for(int i=3;i<=n;i++)
+        {
+            c=a+b;
+            if(i==n)
+            {
+            System.out.print(c);
+            break;
+            }
+            a=b;b=c;
+        }
+    }
+}
diff --git a/December 05/question5.txt b/December 05/question5.txt
new file mode 100644
index 0000000..ba03fcd
--- /dev/null
+++ b/December 05/question5.txt	
@@ -0,0 +1,24 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s=new Scanner(System.in);
+       int n=s.nextInt();
+       int k=s.nextInt();
+       solution(n,k);
+    }
+    public static void solution(int n,int k)
+    {
+        List<Integer>l1=new ArrayList<>();
+        for(int i=0;i<n;i++)
+        {
+            l1.add(i);
+        }
+        int j=0;
+        while(l1.size()>1)
+        {
+            j=(j+k-1)%l1.size();
+            l1.remove(j);
+        }
+        System.out.print(l1.get(0));
+    }   
+}
diff --git a/December 06/question6.txt b/December 06/question6.txt
new file mode 100644
index 0000000..1d39407
--- /dev/null
+++ b/December 06/question6.txt	
@@ -0,0 +1,31 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int target=s.nextInt();
+        int[] arr=new int[n];
+        for(int i=0;i<n;i++)
+        {
+            arr[i]=s.nextInt();
+        }
+        solution(arr,target);
+    }
+    public static void solution(int[] arr,int target)
+    {
+        int n=arr.length;
+        HashMap<Integer,Integer>h1=new HashMap<>();
+        HashSet<int[]> set = new HashSet<>();
+        for (int i = 0; i <arr.length; i++) {
+            int complement = target - arr[i];
+            if (h1.containsValue(complement)) {
+                set.add(new int[]{complement,arr[i]});
+            }
+            h1.put(i,arr[i]);
+        }
+         for(int[] s:set)
+        {
+            System.out.println(Arrays.toString(s));
+        }
+    }
+}
diff --git a/December 07/question7.txt b/December 07/question7.txt
new file mode 100644
index 0000000..6389223
--- /dev/null
+++ b/December 07/question7.txt	
@@ -0,0 +1,27 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s=new Scanner(System.in);
+       int n=s.nextInt();
+       solution(n);
+    }
+    public static void solution(int n)
+    {
+        List<List<Integer>>l1=new ArrayList<>();
+        for(int i=0;i<n;i++)
+        {
+            List<Integer>cur=new ArrayList<>();
+            cur.add(1);
+            for(int j=1;j<i;j++)
+            {
+                int val=l1.get(i-1).get(j-1)+l1.get(i-1).get(j);
+                cur.add(val);
+            }
+            if(i>0)
+            cur.add(1);
+            
+            l1.add(cur);
+        }
+        System.out.print(l1);
+    }
+}
diff --git a/December 08/question8.txt b/December 08/question8.txt
new file mode 100644
index 0000000..8ba91c7
--- /dev/null
+++ b/December 08/question8.txt	
@@ -0,0 +1,25 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s=new Scanner(System.in);
+       int n=s.nextInt();
+       solution(n);
+    }
+    public static void solution(int n)
+    {
+        int s,res=0,j;
+        for(int i=1;i<=n;i++)
+        { 
+            s=0;
+            j=i;
+            while(j>0)
+            {
+            int r=j%10;
+            s+=r*r;
+            j/=10;
+            }
+            res+=s;
+        }
+        System.out.print(res);
+    }
+}
diff --git a/December 09/question9.txt b/December 09/question9.txt
new file mode 100644
index 0000000..6db2474
--- /dev/null
+++ b/December 09/question9.txt	
@@ -0,0 +1,24 @@
+import java.util.*;
+class Main {
+	public static void main(String[] args) {
+		Scanner s=new Scanner(System.in);
+		int n=s.nextInt();
+		List<Integer>l1=new ArrayList<>();
+		for(int i=0; i<n; i++)
+		{
+		    l1.add(s.nextInt());
+		}
+		solution(l1);
+	}
+	public static void solution(List<Integer>l1)
+	{             int c=0;
+		for(int i=0; i<l1.size(); i++)
+		{
+			if(l1.get(i)==1)
+			{
+				c++;
+			}
+		}
+		System.out.print(c);
+	}
+}
diff --git a/December 10/question10.txt b/December 10/question10.txt
new file mode 100644
index 0000000..32b6189
--- /dev/null
+++ b/December 10/question10.txt	
@@ -0,0 +1,59 @@
+from collections import defaultdict
+
+def find_concurrent_jobs(tasks):
+    graph = defaultdict(list)
+    for task, dependencies in tasks:
+        graph[task].extend(dependencies)
+
+    level_map = {}
+    visited = set()
+    current_path = set()
+
+    def dfs(task):
+        if task in current_path:
+            return False
+        if task in visited:
+            return True
+
+        current_path.add(task)
+        max_level = 0
+        for dep in graph[task]:
+            if not dfs(dep):
+                return False
+            max_level = max(max_level, level_map[dep])
+        current_path.remove(task)
+
+        visited.add(task)
+        level_map[task] = max_level + 1
+        return True
+
+    for task, _ in tasks:
+        if task not in visited:
+            if not dfs(task):
+                return "Error: Cyclic dependency detected"
+
+    result = defaultdict(list)
+    for task, level in level_map.items():
+        result[level].append(task)
+
+    return [result[level] for level in sorted(result)]
+
+def get_tasks_from_user():
+    tasks = []
+    while True:
+        task = input("Enter task name (or 'done' to finish): ").strip()
+        if task.lower() == "done":
+            break
+        dependencies = input(f"Enter dependencies for task '{task}' (comma-separated, or leave blank if none): ").strip()
+        dependencies_list = dependencies.split(",") if dependencies else []
+        dependencies_list = [dep.strip() for dep in dependencies_list if dep.strip()]
+        tasks.append((task, dependencies_list))
+    return tasks
+
+tasks = get_tasks_from_user()
+result = find_concurrent_jobs(tasks)
+if isinstance(result, str):
+    print(result)
+else:
+    for level, jobs in enumerate(result, 1):
+        print(f"Level {level}: {', '.join(jobs)}")
diff --git a/December 11/question11.txt b/December 11/question11.txt
new file mode 100644
index 0000000..e4376aa
--- /dev/null
+++ b/December 11/question11.txt	
@@ -0,0 +1,28 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        String s1=s.nextLine();
+        solution(s1);
+    }
+    public static void solution(String s)
+    {
+        int org=0;
+        for(int i=0;i<s.length();i++)
+        {
+            char ch=s.charAt(i);
+            if(ch=='R')
+            org++;
+            if(ch=='L')
+            org--;
+            if(ch=='U')
+            org++;
+            if(ch=='D')
+            org--;
+        }
+        if(org==0)
+        System.out.print("true");
+        else
+        System.out.print("false");
+            }
+}
diff --git a/December 12/question12.txt b/December 12/question12.txt
new file mode 100644
index 0000000..f1b942b
--- /dev/null
+++ b/December 12/question12.txt	
@@ -0,0 +1,52 @@
+from collections import deque
+
+def process_ticket_requests(N, requests):
+    vip_queue = deque()
+    regular_queue = deque()
+    remaining_tickets = N
+    results = []
+
+    for request in requests:
+        name, tickets, *priority = request.split()
+        tickets = int(tickets)
+        if "VIP" in priority:
+            vip_queue.append((name, tickets))
+        else:
+            regular_queue.append((name, tickets))
+
+    def process_queue(queue):
+        nonlocal remaining_tickets
+        while queue and remaining_tickets > 0:
+            name, tickets = queue.popleft()
+            if tickets <= remaining_tickets:
+                remaining_tickets -= tickets
+                results.append(f"{name} purchased {tickets} tickets")
+            else:
+                results.append(f"{name} purchased {remaining_tickets} tickets")
+                remaining_tickets = 0
+
+    process_queue(vip_queue)
+    process_queue(regular_queue)
+
+    for queue in [vip_queue, regular_queue]:
+        while queue:
+            name, _ = queue.popleft()
+            results.append(f"{name} was not served")
+
+    return results
+
+def get_dynamic_input():
+    N = int(input("Enter the total number of tickets available: "))
+    requests = []
+    print("Enter ticket requests (name, number of tickets, optional VIP). Type 'done' to finish:")
+    while True:
+        request = input().strip()
+        if request.lower() == "done":
+            break
+        requests.append(request)
+    return N, requests
+
+N, requests = get_dynamic_input()
+output = process_ticket_requests(N, requests)
+for line in output:
+    print(line)
diff --git a/December 13/question13.txt b/December 13/question13.txt
new file mode 100644
index 0000000..ea16357
--- /dev/null
+++ b/December 13/question13.txt	
@@ -0,0 +1,41 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        List<Integer>l1=new ArrayList<>();
+        for(int i=0;i<n;i++)
+        {
+            l1.add(s.nextInt());
+        }
+        solution(l1);
+    }
+    public static void solution(List<Integer>l1)
+    {
+        int s,pre=0,c=0,j,x=0;
+        for(int i=0;i<l1.size()-1;i++)
+        {
+            s=l1.get(i);
+            x=i;
+            for(j=i+1;j<l1.size();j++)
+            {
+                if(s>l1.get(j))
+            {
+                s=l1.get(j);
+                x=j;
+            }
+            }
+           if(s!=pre && i != x&& swap(i,x,l1))
+            c++;
+            pre=s;
+        }
+        System.out.print(c);
+    }
+    public static boolean swap(int i,int j,List<Integer>l1)
+    {
+        int temp = l1.get(i); 
+        l1.set(i, l1.get(j)); 
+        l1.set(j, temp);
+        return true;
+    }
+}
diff --git a/December 14/question14.txt b/December 14/question14.txt
new file mode 100644
index 0000000..98a70bb
--- /dev/null
+++ b/December 14/question14.txt	
@@ -0,0 +1,53 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int test = sc.nextInt(); 
+        StringBuilder result = new StringBuilder();
+        while (test-- > 0) {
+            int n = sc.nextInt(); 
+            int k = sc.nextInt();
+            int d = sc.nextInt(); 
+            int[] arr = new int[n];
+            for (int i = 0; i < n; i++) {
+                arr[i] = sc.nextInt();
+            }
+            if (cal(n,k,d,arr)) {
+                result.append("yes\n");
+            } else {
+                result.append("no\n");
+            }
+        }
+        System.out.println(result);
+        sc.close();
+    }
+
+    public static boolean cal(int n, int k, int d, int[] arr) {
+         HashMap<Integer, Integer> h1 = new HashMap<>();
+        for (int num : arr) {
+            h1.put(num, h1.getOrDefault(num, 0) + 1);
+        }
+        if (h1.size() < k) 
+        return false;
+        HashSet<Integer> team1 = new HashSet<>();
+        int[] freq = new int[n + 1];
+        int l = 0;
+        for (int r = 0; r < n; r++) {
+            freq[arr[r]]++;
+            team1.add(arr[r]);
+            while (team1.size() > k) {
+                freq[arr[l]]--;
+                if (freq[arr[l]] == 0) {
+                    team1.remove(arr[l]);
+                }
+                l++;
+            }
+            int team1_size = r - l + 1;
+            int team2_size= n - team1_size;
+            if (Math.abs(team1_size - team2_size) <= d && team1.size() == k) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
diff --git a/December 15/question15.txt b/December 15/question15.txt
new file mode 100644
index 0000000..2ae56f7
--- /dev/null
+++ b/December 15/question15.txt	
@@ -0,0 +1,30 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int[] arr=new int[n];
+        int w=s.nextInt();
+        for(int i=0;i<n;i++)
+        {
+            arr[i]=s.nextInt();
+        }
+        solution(arr,w);
+    }
+    public static void solution(int[] arr,int w)
+    {
+        int s=0,t=0;
+        for(int i=0;i<arr.length;i++)
+        {
+           
+            if((s+=arr[i])>w)
+            {
+                s=arr[i];
+                t++;
+            }
+        }
+        if(s>0)
+        t++;
+        System.out.print(t);
+    }
+}
diff --git a/December 16/question16.txt b/December 16/question16.txt
new file mode 100644
index 0000000..25feeed
--- /dev/null
+++ b/December 16/question16.txt	
@@ -0,0 +1,41 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s1=new Scanner(System.in);
+       int n=s1.nextInt();
+       int n1=s1.nextInt();
+       int[] arrival=new int[n];
+       int[] departure=new int[n1];
+       for(int i=0;i<n;i++)
+       arrival[i]=s1.nextInt();
+       for(int i=0;i<n;i++)
+       departure[i]=s1.nextInt();
+       int c=0;
+        for(int i=0;i<n-1;i++)    
+        {
+            for(int j=i+1;j<n;j++)
+            if(arrival[i]>arrival[j])
+            {
+                int temp=arrival[i];
+                arrival[i]=arrival[j];
+                arrival[j]=temp;
+                
+                int temp1=departure[i];
+                departure[i]=departure[j];
+                departure[j]=temp1;
+            }
+        }
+       int min = arrival[0];
+       int max=departure[0];
+       for(int i=1;i<n;i++)
+       {
+           if(max>arrival[i])
+           c++;
+           else
+           {
+               min=arrival[i];
+               max=departure[i];
+           }
+       }
+       System.out.println(c);
+    }   }
diff --git a/December 18/question18.txt b/December 18/question18.txt
new file mode 100644
index 0000000..fd5fc27
--- /dev/null
+++ b/December 18/question18.txt	
@@ -0,0 +1,41 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner ss=new Scanner(System.in);
+       String s=ss.next();
+        int start=0,end=0;
+        for(int i=0;i<s.length();i++)
+        {
+            int l1=cal(s,i,i);
+            int l2=cal(s,i,i+1);
+            int total=Math.max(l1,l2);
+            if(total>end-start)
+            {
+                start=i-((total-1)/2);
+                end=i+(total/2);
+            }
+        }
+        String newstr= s.substring(start,end+1);
+        int c=0;
+        for(int i=0;i<newstr.length();i++)
+        {
+            if(newstr.charAt(i)=='R')
+            c+=250;
+            if(newstr.charAt(i)=='D')
+            c+=500;
+            if(newstr.charAt(i)=='E')
+            c+=100;
+        }
+        System.out.print("$"+c);
+    }
+    public static int cal(String s,int l,int r)
+    {
+        if(s==null || l>r)
+        return 0;
+        while(l>=0 && r<s.length() && s.charAt(l) == s.charAt(r))
+        {
+            l--;
+            r++;
+        }
+        return r-l-1;
+    }       }
diff --git a/December 19/question19.txt b/December 19/question19.txt
new file mode 100644
index 0000000..ed6446a
--- /dev/null
+++ b/December 19/question19.txt	
@@ -0,0 +1,23 @@
+import java.util.*;
+class Main {
+    public static void solve(int n, char start, char dest, char help) {
+        if (n == 1) {
+            System.out.println("Move disk 1 from " + start + " to " + dest);
+            return;
+        }
+        solve(n - 1, start, help, dest);
+        System.out.println("Move disk " + n + " from " + start + " to " + dest);
+        solve(n - 1, help, dest, start);
+    }
+    public static void main(String[] args) {
+        Scanner s = new Scanner(System.in);
+        int n = s.nextInt();
+        char start = s.next().charAt(0);
+        char destination = s.next().charAt(0);
+        char helper = s.next().charAt(0);
+        System.out.println("Minimum number of moves: " + ((int) Math.pow(2, n) - 1));
+        System.out.println("Sequence of moves:");
+        solve(n, start, destination, helper);
+        s.close();
+    }
+}
diff --git a/December 20/question20.txt b/December 20/question20.txt
new file mode 100644
index 0000000..fd928d7
--- /dev/null
+++ b/December 20/question20.txt	
@@ -0,0 +1,39 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s=new Scanner(System.in);
+        int n=s.nextInt();
+        int target=s.nextInt();
+        int[] arr=new int[n];
+        for(int i=0;i<n;i++)
+        {
+            arr[i]=s.nextInt();
+        }
+        List<List<Integer>>l1=new ArrayList<>();
+        l1=solution(arr,target);
+        System.out.print(l1.size());
+    }
+    public static List<List<Integer>> solution(int[] arr,int t)
+    {
+        List<List<Integer>>l2=new ArrayList<>();
+        comb(arr,t,l2,new ArrayList<>());
+        return l2;
+    }
+    public static void comb(int[] arr,int t,List<List<Integer>> l2,List<Integer> cur)
+    {
+        if(t==0)
+        {
+            l2.add(new ArrayList<>(cur));
+            return;
+        }
+      for(int ind=0;ind<arr.length;ind++)
+      {
+        if(arr[ind]<=t)
+        {
+            cur.add(arr[ind]);
+            comb(arr,t-arr[ind],l2,cur);
+            cur.remove(cur.size()-1);
+        }
+      }
+    }
+}
diff --git a/December 23/question23.txt b/December 23/question23.txt
new file mode 100644
index 0000000..6285c62
--- /dev/null
+++ b/December 23/question23.txt	
@@ -0,0 +1,31 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+        Scanner s1=new Scanner(System.in);
+        int n=s1.nextInt();
+        int[][] arr=new int[n][n];
+        int z=1;
+        int s=0;
+        for(int i=0;i<n;i++)
+        {
+            for(int j=0;j<n;j++)
+            {
+            if (i == 0 || i == n - 1 || j == 0 || j == n - 1)
+                s+=z;
+               
+            arr[i][j]=z++;
+            }
+        }
+      
+        int pri=0,sec=0;
+        for(int i=0;i<n;i++)
+        {
+            pri+=arr[i][i];
+            sec+=arr[i][n-1-i];
+        }
+        int diag=Math.abs(pri-sec);
+   
+        int magic=diag+s;
+        System.out.println(magic);
+    }
+}
diff --git a/December 26/question26.txt b/December 26/question26.txt
new file mode 100644
index 0000000..5121e5f
--- /dev/null
+++ b/December 26/question26.txt	
@@ -0,0 +1,28 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s1=new Scanner(System.in);
+       int n=s1.nextInt();
+       int[] arr=new int[n];
+       for(int i=0;i<n;i++)
+       arr[i]=s1.nextInt();
+       int s = 0;  
+       boolean flag=false;
+       for (int i = 0; i < n; i++) {
+            if (i > s) {  
+                flag=false;
+                break;
+            }
+            s = Math.max(s, i + arr[i]);  
+            if (s >= n - 1) {  
+                flag=true;
+                break;
+            }
+        }
+        if(flag)
+       System.out.print("true");
+       else
+       System.out.print("false");
+    }
+}
+
diff --git a/December 27/question27.txt b/December 27/question27.txt
new file mode 100644
index 0000000..22b0194
--- /dev/null
+++ b/December 27/question27.txt	
@@ -0,0 +1,29 @@
+import java.util.*;
+class Main {
+    public static void main(String[] args) {
+       Scanner s=new Scanner(System.in);
+       int n=s.nextInt();
+       int[] arr=new int[n];
+       for(int i=0;i<n;i++)
+       arr[i]=s.nextInt();
+       int leftmax=arr[0];
+        Stack<Integer> rightmax=new Stack();
+        rightmax.push(arr[arr.length-1]);
+        for(int i=arr.length-2;i>=2;i--)
+        {
+            int temp=Math.max(rightmax.peek(),arr[i]);
+            rightmax.push(temp);
+        }
+        int totalwater=0;
+        for(int i=1;i<arr.length-1;i++)
+        {
+            int min=Math.min(rightmax.peek(),leftmax);
+            int temp=min-arr[i];
+            totalwater+=Math.max(0,temp);
+            rightmax.pop();
+            leftmax=Math.max(leftmax,arr[i]);
+        }
+        System.out.print(totalwater);
+    }
+}
+