Added codes for 23 and 24 March

GeeksForGeeks/March/23-3-24/GFG.java

@@ -0,0 +1,42 @@
+//{ Driver Code Starts
+import java.io.*;
+import java.util.*;
+
+class Main {
+    // Driver code
+    public static void main(String[] args) throws Exception {
+        BufferedReader br =
+            new BufferedReader(new InputStreamReader(System.in));
+        int t = Integer.parseInt(br.readLine().trim());
+        while (t-- > 0) {
+            int n = Integer.parseInt(br.readLine().trim());
+            Solution obj = new Solution();
+            int ans[] = obj.Series(n);
+            for (int i : ans) {
+                System.out.print(i + " ");
+            }
+            System.out.println();
+        }
+    }
+}
+// } Driver Code Ends
+
+
+class Solution {
+
+    int[] Series(int n) 
+    {
+        // code here
+        if(n==1)
+            return new int[]{0,1};
+
+        int[] ans=new int[n+1];
+        ans[0]=0;
+        ans[1]=1;
+
+        for(int i=2;i<=n;i++)
+            ans[i] = (ans[i-1]+ans[i-2]) % ((int)Math.pow(10,9)+7);
+
+        return ans;
+    }
+}

GeeksForGeeks/March/23-3-24/README.md

@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(n)

GeeksForGeeks/March/24-3-24/GFG.java

@@ -0,0 +1,63 @@
+//{ Driver Code Starts
+//Initial Template for Java
+import java.io.*;
+import java.util.*;
+
+class GFG {
+    static File file;
+    static BufferedReader in;
+    static PrintWriter out;
+
+    public static void main(String args[]) throws IOException {
+        in=new BufferedReader(new InputStreamReader(System.in));
+        out=new PrintWriter(System.out);
+        int t = Integer.parseInt(in.readLine());
+
+        while (t-- > 0) {
+
+            String s[] = in.readLine().trim().split(" ");
+            int n = Integer.parseInt(s[0]);
+            int x = Integer.parseInt(s[1]);
+            s = in.readLine().trim().split(" ");
+            Stack<Integer> st = new Stack<>();
+            for (int i = 0; i < n; i++) {
+                st.push(Integer.parseInt(s[i]));
+            }
+            Solution ob = new Solution();
+            Stack<Integer> S = ob.insertAtBottom(st, x);
+            for (int i : S) {
+                out.print(i + " ");
+            }
+            out.println();
+        }
+        out.close();
+    }
+}
+
+// } Driver Code Ends
+
+
+//User function Template for Java
+class Solution 
+{
+    public Stack<Integer> insertAtBottom(Stack<Integer> st, int x) 
+    {
+        Stack<Integer> temp = new Stack<>();
+
+        while (!st.empty())
+        {
+            temp.push(st.peek());
+            st.pop();
+        }
+
+        st.push(x);
+
+        while (!temp.empty()) 
+        {
+            st.push(temp.peek());
+            temp.pop();
+        }
+
+        return st;
+    }
+}

GeeksForGeeks/March/24-3-24/README.md

@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(n)

LeetCode/March/23-3-24/README.md

@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(1)

LeetCode/March/23-3-24/Solution.java

@@ -0,0 +1,66 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution 
+{
+    public void reorderList(ListNode head) 
+    {
+        if (head == null || head.next == null)
+            return;
+
+        ListNode mid = findMid(head);
+        ListNode reversed = reverse(mid);
+        merge(head, reversed);
+    }
+
+    private ListNode findMid(ListNode head) 
+    {
+        ListNode prev = null;
+        ListNode slow = head;
+        ListNode fast = head;
+
+        while (fast != null && fast.next != null) 
+        {
+            prev = slow;
+            slow = slow.next;
+            fast = fast.next.next;
+        }
+        prev.next = null;
+
+        return slow;
+    }
+
+    private ListNode reverse(ListNode head) 
+    {
+        ListNode prev = null;
+        ListNode curr = head;
+
+        while (curr != null) 
+        {
+            ListNode next = curr.next;
+            curr.next = prev;
+            prev = curr;
+            curr = next;
+        }
+
+        return prev;
+    }
+
+    private void merge(ListNode l1, ListNode l2) 
+    {
+        while (l2 != null) 
+        {
+            ListNode next = l1.next;
+            l1.next = l2;
+            l1 = l2;
+            l2 = next;
+        }
+    }
+}

LeetCode/March/24-3-24/README.md

@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(1)

LeetCode/March/24-3-24/Solution.java

@@ -0,0 +1,24 @@
+class Solution 
+{
+    public int findDuplicate(int[] nums) 
+    {
+        int slow = nums[nums[0]];
+        int fast = nums[nums[nums[0]]];
+
+        while (slow != fast) 
+        {
+            slow = nums[slow];
+            fast = nums[nums[fast]];
+        }
+
+        slow = nums[0];
+
+        while (slow != fast) 
+        {
+            slow = nums[slow];
+            fast = nums[fast];
+        }
+
+        return slow;
+    }
+}