Merge pull request #226 from shikhar9820/master

Create c++ recursive spiral level order tree traversal

Recursive Algorithms/DFS/c++ recursive spiral level order tree traversal

@@ -0,0 +1,110 @@
+// Recursive C program for level order traversal of Binary Tree
+#include <stdio.h>
+#include <stdlib.h>
+
+/* A binary tree node has data, pointer to left child
+   and a pointer to right child */
+struct node
+{
+    int data;
+    struct node* left, *right;
+};
+
+/* Function protoypes */
+void printGivenLevel(struct node* root, int level,int counter);
+int height(struct node* node);
+struct node* newNode(int data);
+
+/* Function to print level order traversal a tree*/
+void printLevelOrder(struct node* root)
+{
+    int h = height(root);
+    int i,j;
+    for (i=1; i<=h; i++){
+        j=i;
+        printGivenLevel(root,i,j);
+}
+}
+/* Print nodes at a given level */
+void printGivenLevel(struct node* root, int level ,int counter)
+{
+    if (root == NULL)
+        return;
+    if (level == 1)
+        printf("%d ", root->data);
+
+    else if (level > 1 && (counter%2)!=0)
+    {
+        printGivenLevel(root->right, level-1,counter);
+        printGivenLevel(root->left, level-1,counter);
+    }
+
+    else
+    {
+        printGivenLevel(root->left, level-1,counter);
+        printGivenLevel(root->right, level-1,counter);
+    }
+}
+
+/* Compute the "height" of a tree -- the number of
+    nodes along the longest path from the root node
+    down to the farthest leaf node.*/
+int height(struct node* node)
+{
+    if (node==NULL)
+        return 0;
+    else
+    {
+        /* compute the height of each subtree */
+        int lheight = height(node->left);
+        int rheight = height(node->right);
+
+        /* use the larger one */
+        if (lheight > rheight)
+            return(lheight+1);
+        else return(rheight+1);
+    }
+}
+
+/* Helper function that allocates a new node with the
+   given data and NULL left and right pointers. */
+struct node* newNode(int data)
+{
+    struct node* node = (struct node*)
+                        malloc(sizeof(struct node));
+    node->data = data;
+    node->left = NULL;
+    node->right = NULL;
+
+    return(node);
+}
+
+/* Driver program to test above functions*/
+int main()
+{
+    struct node *root = newNode(1);
+    root->left        = newNode(2);
+    root->right       = newNode(3);
+    root->right->left = newNode(1);
+    root->right->right= newNode(9);
+    root->left->left  = newNode(4);
+    root->left->right = newNode(5);
+   root->left->left->left  = newNode(6);
+    root->left->right->left = newNode(8);
+    root->left->right->left->left= newNode(0);
+
+    root->left->right->left->right= newNode(3);
+    root->left->right->left->right->left= newNode(7);
+    root->left->right->left->right->right= newNode(5);
+    root->left->right->left->right->left->left= newNode(9);
+    root->left->right->left->right->left->right= newNode(6);
+
+
+    printf("Level Order traversal of binary tree is \n");
+/*int l;
+    l=height(root);
+printf("%d",l);
+   */
+   printLevelOrder(root);
+    return 0;
+}