Added codes for 20 Jan

GeeksForGeeks/20-1-24/GFG.java

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+//{ Driver Code Starts
+//Initial Template for Java
+
+import java.util.*;
+import java.io.*;
+
+class Node {
+    int data;
+    Node left;
+    Node right;
+    Node(int data) {
+        this.data = data;
+        left = null;
+        right = null;
+    }
+} class GfG {
+    public static Node buildTree(String str) {
+
+        if (str.length() == 0 || str.charAt(0) == 'N') {
+            return null;
+        }
+
+        String ip[] = str.split(" ");
+        // Create the root of the tree
+        Node root = new Node(Integer.parseInt(ip[0]));
+        // Push the root to the queue
+
+        Queue<Node> queue = new LinkedList<>();
+
+        queue.add(root);
+        // Starting from the second element
+
+        int i = 1;
+        while (queue.size() > 0 && i < ip.length) {
+
+            // Get and remove the front of the queue
+            Node currNode = queue.peek();
+            queue.remove();
+
+            // Get the current node's value from the string
+            String currVal = ip[i];
+
+            // If the left child is not null
+            if (!currVal.equals("N")) {
+
+                // Create the left child for the current node
+                currNode.left = new Node(Integer.parseInt(currVal));
+                // Push it to the queue
+                queue.add(currNode.left);
+            }
+
+            // For the right child
+            i++;
+            if (i >= ip.length) break;
+
+            currVal = ip[i];
+
+            // If the right child is not null
+            if (!currVal.equals("N")) {
+
+                // Create the right child for the current node
+                currNode.right = new Node(Integer.parseInt(currVal));
+
+                // Push it to the queue
+                queue.add(currNode.right);
+            }
+            i++;
+        }
+
+        return root;
+    }
+
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br =
+            new BufferedReader(new InputStreamReader(System.in));
+
+        int t = Integer.parseInt(br.readLine().trim());
+
+        while (t-- > 0) {
+
+            String s = br.readLine();
+            Node root = buildTree(s);
+
+            Solution ob=new Solution();
+            System.out.println( ob.distributeCandy(root));
+
+        }
+    }
+}
+// } Driver Code Ends
+
+
+//User function Template for Java
+
+/*
+class Node {
+    int data;
+    Node left;
+    Node right;
+    Node(int data) {
+        this.data = data;
+        left = null;
+        right = null;
+    }
+}*/
+
+
+class Solution
+{
+    static int ans;
+
+    public static int distributeCandy(Node root)
+    {
+        //code here
+        ans = 0;
+        helper(root);
+        return ans;
+    }
+
+
+    private static int helper(Node root)
+    {
+        if (root == null)
+            return 0;
+
+        int l = helper(root.left);
+
+        int r = helper(root.right);
+
+        ans += Math.abs(l) + Math.abs(r);
+
+        return root.data + l + r - 1;
+    }
+}

GeeksForGeeks/20-1-24/README.md

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

LeetCode/20-1-24/README.md

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

LeetCode/20-1-24/Solution.java

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+class Solution 
+{
+    public int sumSubarrayMins(int[] arr) 
+    {
+        final int kMod = 1_000_000_007;
+        final int n = arr.length;
+        long ans = 0;
+
+        int[] prevMin = new int[n];
+        int[] nextMin = new int[n];
+        Deque<Integer> stack = new ArrayDeque<>();
+
+        Arrays.fill(prevMin, -1);
+        Arrays.fill(nextMin, n);
+
+        for (int i = 0; i < arr.length; ++i) 
+        {
+            while (!stack.isEmpty() && arr[stack.peek()] > arr[i]) 
+            {
+                final int index = stack.pop();
+                nextMin[index] = i;
+            }
+
+            if (!stack.isEmpty())
+                prevMin[i] = stack.peek();
+
+            stack.push(i);
+        }
+
+        for (int i = 0; i < arr.length; ++i) 
+        {
+            ans += (long) arr[i] * (i - prevMin[i]) * (nextMin[i] - i);
+            ans %= kMod;
+        }
+
+        return (int) ans;
+    }
+}