Added codes for 28 April

GeeksForGeeks/April/28-4-24/GFG.java

@@ -0,0 +1,85 @@
+//{ Driver Code Starts
+import java.util.*;
+import java.io.*;
+
+class Node{
+    int data;
+    Node next;
+
+    Node(int x){
+        data = x;
+        next = null;
+    }
+
+}
+class GFG{
+	static void printList(Node node) 
+	{ 
+		while (node != null) 
+		{ 
+			System.out.print(node.data + " "); 
+			node = node.next; 
+		} 
+		System.out.println(); 
+	}
+    public static void main(String args[]) throws IOException { 
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t > 0){
+        	int n = sc.nextInt();
+            Node head = new Node(sc.nextInt());
+            Node tail = head;
+            for(int i=0; i<n-1; i++)
+            {
+                tail.next = new Node(sc.nextInt());
+                tail = tail.next;
+            }
+            Solution g = new Solution();
+            head = g.deleteMid(head);
+            printList(head); 
+            t--;
+        }
+    } 
+} 
+
+
+// } Driver Code Ends
+
+
+/*
+class Node {
+    int data;
+    Node next;
+    Node(int d)  { data = d;  next = null; }
+}
+*/
+
+class Solution 
+{
+    Node deleteMid(Node head) 
+    {
+        // This is method only submission.
+        // You only need to complete the method.
+        if (head == null) 
+            return null; 
+        if (head.next == null)
+            return null; 
+
+        Node slow = head; 
+        Node fast = head; 
+
+        Node prev = null; 
+
+        while (fast != null && fast.next != null) 
+        { 
+            fast = fast.next.next; 
+            prev = slow; 
+            slow = slow.next; 
+        } 
+
+        // Delete the middle node 
+        prev.next = slow.next;
+
+        return head;
+    }
+}

GeeksForGeeks/April/28-4-24/README.md

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

LeetCode/April/28-4-24/README.md

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

LeetCode/April/28-4-24/Solution.java

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+class Solution 
+{
+    public int[] sumOfDistancesInTree(int n, int[][] edges) 
+    {
+        int[] ans = new int[n];
+        int[] count = new int[n];
+        Set<Integer>[] tree = new Set[n];
+
+        Arrays.fill(count, 1);
+
+        for (int i = 0; i < n; ++i)
+            tree[i] = new HashSet<>();
+
+        for (int[] edge : edges) 
+        {
+            int u = edge[0];
+            int v = edge[1];
+            tree[u].add(v);
+            tree[v].add(u);
+        }
+
+        postorder(tree, 0, -1, count, ans);
+        preorder(tree, 0, -1, count, ans);
+        return ans;
+    }
+
+    private void postorder(Set<Integer>[] tree, int node, int parent, int[] count, int[] ans) 
+    {
+        for (int child : tree[node])
+        {
+            if (child == parent)
+                continue;
+
+            postorder(tree, child, node, count, ans);
+            count[node] += count[child];
+            ans[node] += ans[child] + count[child];
+        }
+    }
+
+    private void preorder(Set<Integer>[] tree, int node, int parent, int[] count, int[] ans) 
+    {
+        for (int child : tree[node]) 
+        {
+            if (child == parent)
+                continue;
+
+            ans[child] = ans[node] - count[child] + (tree.length - count[child]);
+            preorder(tree, child, node, count, ans);
+        }
+    }
+}