From eeec2c36cb70a468bbf8258468c22c7dd9d68919 Mon Sep 17 00:00:00 2001
From: Tanmay-312 <jain2002tj@gmail.com>
Date: Sun, 28 Apr 2024 09:18:11 +0530
Subject: [PATCH] Added codes for 28 April

---
 GeeksForGeeks/April/28-4-24/GFG.java  | 85 +++++++++++++++++++++++++++
 GeeksForGeeks/April/28-4-24/README.md |  2 +
 LeetCode/April/28-4-24/README.md      |  2 +
 LeetCode/April/28-4-24/Solution.java  | 51 ++++++++++++++++
 4 files changed, 140 insertions(+)
 create mode 100644 GeeksForGeeks/April/28-4-24/GFG.java
 create mode 100644 GeeksForGeeks/April/28-4-24/README.md
 create mode 100644 LeetCode/April/28-4-24/README.md
 create mode 100644 LeetCode/April/28-4-24/Solution.java

diff --git a/GeeksForGeeks/April/28-4-24/GFG.java b/GeeksForGeeks/April/28-4-24/GFG.java
new file mode 100644
index 0000000..11bc99a
--- /dev/null
+++ b/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;
+    }
+}
diff --git a/GeeksForGeeks/April/28-4-24/README.md b/GeeksForGeeks/April/28-4-24/README.md
new file mode 100644
index 0000000..9567f26
--- /dev/null
+++ b/GeeksForGeeks/April/28-4-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(1)
diff --git a/LeetCode/April/28-4-24/README.md b/LeetCode/April/28-4-24/README.md
new file mode 100644
index 0000000..7384c4b
--- /dev/null
+++ b/LeetCode/April/28-4-24/README.md
@@ -0,0 +1,2 @@
+Time complexity - O(n)
+Space complexity - O(n)
diff --git a/LeetCode/April/28-4-24/Solution.java b/LeetCode/April/28-4-24/Solution.java
new file mode 100644
index 0000000..39ce5f9
--- /dev/null
+++ b/LeetCode/April/28-4-24/Solution.java
@@ -0,0 +1,51 @@
+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);
+        }
+    }
+}