Added files

Author: avidLearnerInProgress

amazon/print_extreme_nodes_binary_tree.cpp

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+{
+/* C++ program to print nodes of extreme corners
+of each level in alternate order */
+#include <bits/stdc++.h>
+using namespace std;
+/* A binary tree node has data, pointer to left child
+and a pointer to right child */
+struct Node
+{
+	int data;
+	struct Node *left;
+	struct Node *right;
+	
+	Node(int x){
+	    data = x;
+	    left = NULL;
+	    right = NULL;
+	}
+};
+/* Function to print nodes of extreme corners
+of each level in alternate order */
+void printExtremeNodes(Node* root);
+/* Driver program to test above functions*/
+int main()
+{
+   int t;
+  scanf("%d
+", &t);
+  while (t--)
+  {
+     map<int, Node*> m;
+     int n;
+     scanf("%d
+",&n);
+     Node *root = NULL;
+     while (n--)
+     {
+        Node *parent;
+        char lr;
+        int n1, n2;
+        scanf("%d %d %c", &n1, &n2, &lr);
+      //  cout << n1 << " " << n2 << " " << (char)lr << endl;
+        if (m.find(n1) == m.end())
+        {
+           parent = new Node(n1);
+           m[n1] = parent;
+           if (root == NULL)
+             root = parent;
+        }
+        else
+           parent = m[n1];
+        Node *child = new Node(n2);
+        if (lr == 'L')
+          parent->left = child;
+        else
+          parent->right = child;
+        m[n2]  = child;
+     }
+   printExtremeNodes(root);
+   cout<<endl;
+  }
+    return 0;
+}
+
+}
+/*This is a function problem.You only need to complete the function given below*/
+/*
+ A binary tree node has data, pointer to left child
+   and a pointer to right child 
+struct Node
+{
+    int data;
+    Node* left;
+    Node* right;
+};
+*/
+/* Function to print nodes of extreme corners
+of each level in alternate order */
+void printExtremeNodes(Node* root)
+{
+    // Your code here
+    if(!root) return;
+    
+    queue<Node *> q;
+    q.push(root);
+    bool leftToRight = false;
+    while(!q.empty()){
+        int q_size = q.size();
+        int nc = q_size;
+        while(nc--){
+            Node *top = q.front();
+            if(top->left)
+                q.push(top->left);
+            if(top->right)
+                q.push(top->right);
+            q.pop();
+            
+            if(leftToRight && nc == q_size -1)
+                cout<<top->data<<" ";
+            if(!leftToRight && nc == 0)
+                cout<<top->data<<" ";
+        }
+        leftToRight = !leftToRight;
+    }
+}