Added codes for 4 May

GeeksForGeeks/May/04-5-24/GFG.java

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+//{ Driver Code Starts
+import java.util.*;
+
+class Node {
+    int data;
+    Node left;
+    Node right;
+
+    Node(int value) {
+        data = value;
+        left = null;
+        right = null;
+    }
+}
+
+class InorderPostorderToTree {
+    public void preOrder(Node root) {
+        if (root == null) return;
+
+        System.out.print(root.data + " ");
+        preOrder(root.left);
+
+        preOrder(root.right);
+    }
+
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        InorderPostorderToTree ip = new InorderPostorderToTree();
+        int T = sc.nextInt();
+        while (T > 0) {
+            int n = sc.nextInt();
+            int inorder[] = new int[n];
+            int postorder[] = new int[n];
+            for (int i = 0; i < n; i++) inorder[i] = sc.nextInt();
+            for (int i = 0; i < n; i++) postorder[i] = sc.nextInt();
+            GfG g = new GfG();
+            Node root = g.buildTree(inorder, postorder, n);
+            ip.preOrder(root);
+            System.out.println();
+
+            T--;
+        }
+    }
+}
+
+// } Driver Code Ends
+
+
+/* Tree node structure
+class Node
+{
+    int data;
+    Node left;
+    Node right;
+
+        Node(int value)
+    {
+        data = value;
+        left = null;
+        right = null;
+    }
+}*/
+
+
+class GfG 
+{
+    private static int findPos(int[] in, int inStart, int inEnd, int elem) 
+    {
+        for (int i = inStart; i <= inEnd; i++) 
+        {
+            if (in[i] == elem) 
+            {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    private static Node solve(int[] in, int[] post, int[] postIdx, int inStart, int inEnd, int n) 
+    {
+        if (postIdx[0] < 0 || inStart > inEnd) 
+        {
+            return null;
+        }
+
+        int elem = post[postIdx[0]--];
+        Node root = new Node(elem);
+        int pos = findPos(in, inStart, inEnd, elem);
+
+        root.right = solve(in, post, postIdx, pos + 1, inEnd, n);
+        root.left = solve(in, post, postIdx, inStart, pos - 1, n);
+
+        return root;
+    }
+
+    // Function to return a tree created from postorder and inorder traversals.
+    Node buildTree(int in[], int post[], int n) 
+    {
+        int[] postIdx = new int[]{n - 1};
+        return solve(in, post, postIdx, 0, n - 1, n);
+    }
+}

GeeksForGeeks/May/04-5-24/README.md

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

LeetCode/May/04-5-24/README.md

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+Time complexity - O(|sort|)
+Space complexity - O(|sort|)
+
+|sort| = n * logn

LeetCode/May/04-5-24/Solution.java

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+class Solution {
+    public int numRescueBoats(int[] people, int limit) {
+        int ans = 0;
+
+        Arrays.sort(people);
+
+        for (int i = 0, j = people.length - 1; i <= j; ++ans) 
+        {
+            int remain = limit - people[j--];
+            if (people[i] <= remain)
+                ++i;
+        }
+
+        return ans;
+    }
+}