Added codes for 7 March

GeeksForGeeks/March/07-3-24/GFG.java

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+//{ Driver Code Starts
+//Initial Template for Java
+
+import java.io.*;
+import java.util.*;
+
+class GFG {
+    public static void main(String args[]) throws IOException {
+        BufferedReader read =
+            new BufferedReader(new InputStreamReader(System.in));
+        int t = Integer.parseInt(read.readLine());
+        while (t-- > 0) {
+            int N = Integer.parseInt(read.readLine());
+            String S = read.readLine();
+
+            Solution ob = new Solution();
+            System.out.println(ob.longestSubstring(S, N));
+        }
+    }
+}
+
+// } Driver Code Ends
+
+
+//User function Template for Java
+
+class Solution 
+{
+    static String longestSubstring(String s, int n) 
+    {
+        // code here
+        int[][] dp = new int[n + 1][n + 1];
+        int max = 0;
+        int index = 0;
+
+        for(int i = 1; i <= n ; i++)
+        {
+            for(int j = i + 1; j <= n; j++)
+            {
+                if(s.charAt(i - 1) == s.charAt(j - 1) && j - i > dp[i - 1][j - 1])
+                {
+                    dp[i][j] = dp[i - 1][j - 1] + 1;
+
+                    if(dp[i][j] > max)
+                    {
+                        max = dp[i][j];
+                        index = Math.max(i, index);
+                    }
+                }
+
+                else
+                    dp[i][j] = 0;
+            }
+        }
+
+        return max > 0 ? s.substring(index - max, index ) : "-1";
+    }
+};

GeeksForGeeks/March/07-3-24/README.md

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+Time complexity - O(n^2)
+Space complexity - O(n^2)

LeetCode/March/07-3-24/README.md

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+Time complexity - O(n)
+Space complexity - O(1)

LeetCode/March/07-3-24/Solution.java

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+/**
+ * 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 ListNode middleNode(ListNode head) 
+    {
+        if (head==null)
+            return null;
+
+        ListNode slow = head;
+        ListNode fast = head;
+
+        while (fast != null && fast.next != null) 
+        {
+            slow = slow.next;
+            fast = fast.next.next;
+        }
+
+        return slow;
+    }
+}