Added max_sum_across_levels

Author: avidLearnerInProgress

amazon/max_sum_across_levels_binary_tree.cpp

@@ -0,0 +1,113 @@
+{
+#include <bits/stdc++.h>
+using namespace std;
+struct Node
+{
+	int data;
+	struct Node *left;
+	struct Node *right;
+	
+	Node(int x){
+	    data = x;
+	    left = NULL;
+	    right = NULL;
+	}
+};
+/* Computes the number of nodes in a tree. */
+int height(struct Node* node)
+{
+  if (node==NULL)
+    return 0;
+  else
+    return 1 + max(height(node->left), height(node->right));
+}
+int maxLevelSum(Node * root);
+/* Function to get diameter of a binary tree */
+void inorder(Node *root)
+{
+    if (root == NULL)
+       return;
+    inorder(root->left);
+    cout << root->data << " ";
+    inorder(root->right);    
+}
+/* Driver program to test size function*/
+int main()
+{
+  int t;
+  scanf("%d
+", &t);
+  while (t--)
+  {
+     map<int, Node*> m;
+     int n;
+     scanf("%d",&n);
+     struct Node *root = NULL;
+     struct Node *child;
+     while (n--)
+     {
+        Node *parent;
+        char lr;
+        int n1, n2;
+        scanf("%d %d %c", &n1, &n2, &lr);
+        if (m.find(n1) == m.end())
+        {
+           parent = new Node(n1);
+           m[n1] = parent;
+           if (root == NULL)
+             root = parent;
+        }
+        else
+           parent = m[n1];
+        child = new Node(n2);
+        if (lr == 'L')
+          parent->left = child;
+        else
+          parent->right = child;
+        m[n2]  = child;
+     }
+     cout << maxLevelSum(root) << endl;
+  }
+  return 0;
+}
+
+}
+/*This is a function problem.You only need to complete the function given below*/
+/* Tree node structure  used in the program
+ struct Node
+ {
+     int data;
+     Node* left, *right;
+}; */
+/*You are required to complete below method */
+
+
+int maxLevelSum(Node * root)
+{
+    //Your code here
+    if(!root) return 0;
+    
+    queue<Node* > q;
+    q.push(root);
+    
+    int max_sum = root->data, curr_sum = 0;
+    while(!q.empty()){
+        curr_sum = 0;
+        int nodeCount = q.size();
+        while(nodeCount > 0){
+           
+            Node *currNode = q.front();
+            q.pop();
+            curr_sum += currNode->data;
+            
+            if (currNode->left != NULL) 
+                q.push(currNode->left); 
+        
+            if (currNode->right != NULL) 
+                q.push(currNode->right);     
+            nodeCount--;
+        }
+        max_sum = max(curr_sum, max_sum);
+    }
+    return max_sum;
+}