Solved issues.

c/ds/avl_tree.c

@@ -0,0 +1,271 @@
+#include<stdio.h>
+
+typedef struct node
+{
+	int data;
+	struct node *left,*right;
+	int ht;
+}node;
+
+node *insert(node *,int);
+node *Delete(node *,int);
+void preorder(node *);
+void inorder(node *);
+int height( node *);
+node *rotateright(node *);
+node *rotateleft(node *);
+node *RR(node *);
+node *LL(node *);
+node *LR(node *);
+node *RL(node *);
+int BF(node *);
+
+int main()
+{
+	node *root=NULL;
+	int x,n,i,op;
+
+	do
+	{
+		printf("\n1)Create:");
+		printf("\n2)Insert:");
+		printf("\n3)Delete:");
+		printf("\n4)Print:");
+		printf("\n5)Quit:");
+		printf("\n\nEnter Your Choice:");
+		scanf("%d",&op);
+
+		switch(op)
+		{
+			case 1: printf("\nEnter no. of elements:");
+					scanf("%d",&n);
+					printf("\nEnter tree data:");
+					root=NULL;
+					for(i=0;i<n;i++)
+					{
+						scanf("%d",&x);
+						root=insert(root,x);
+					}
+					break;
+
+			case 2: printf("\nEnter a data:");
+					scanf("%d",&x);
+					root=insert(root,x);
+					break;
+
+			case 3: printf("\nEnter a data:");
+					scanf("%d",&x);
+					root=Delete(root,x);
+					break;
+
+			case 4: printf("\nPreorder sequence:\n");
+					preorder(root);
+					printf("\n\nInorder sequence:\n");
+					inorder(root);
+					printf("\n");
+					break;			
+		}
+	}while(op!=5);
+
+	return 0;
+}
+
+node * insert(node *T,int x)
+{
+	if(T==NULL)
+	{
+		T=(node*)malloc(sizeof(node));
+		T->data=x;
+		T->left=NULL;
+		T->right=NULL;
+	}
+	else
+		if(x > T->data)		// insert in right subtree
+		{
+			T->right=insert(T->right,x);
+			if(BF(T)==-2)
+				if(x>T->right->data)
+					T=RR(T);
+				else
+					T=RL(T);
+		}
+		else
+			if(x<T->data)
+			{
+				T->left=insert(T->left,x);
+				if(BF(T)==2)
+					if(x < T->left->data)
+						T=LL(T);
+					else
+						T=LR(T);
+			}
+
+		T->ht=height(T);
+
+		return(T);
+}
+
+node * Delete(node *T,int x)
+{
+	node *p;
+
+	if(T==NULL)
+	{
+		return NULL;
+	}
+	else
+		if(x > T->data)		// insert in right subtree
+		{
+			T->right=Delete(T->right,x);
+			if(BF(T)==2)
+				if(BF(T->left)>=0)
+					T=LL(T);
+				else
+					T=LR(T);
+		}
+		else
+			if(x<T->data)
+			{
+				T->left=Delete(T->left,x);
+				if(BF(T)==-2)	//Rebalance during windup
+					if(BF(T->right)<=0)
+						T=RR(T);
+					else
+						T=RL(T);
+			}
+			else
+			{
+				//data to be deleted is found
+				if(T->right!=NULL)
+				{	//delete its inorder succesor
+					p=T->right;
+
+					while(p->left!= NULL)
+						p=p->left;
+
+					T->data=p->data;
+					T->right=Delete(T->right,p->data);
+
+					if(BF(T)==2)//Rebalance during windup
+						if(BF(T->left)>=0)
+							T=LL(T);
+						else
+							T=LR(T);\
+				}
+				else
+					return(T->left);
+			}
+	T->ht=height(T);
+	return(T);
+}
+
+int height(node *T)
+{
+	int lh,rh;
+	if(T==NULL)
+		return(0);
+
+	if(T->left==NULL)
+		lh=0;
+	else
+		lh=1+T->left->ht;
+
+	if(T->right==NULL)
+		rh=0;
+	else
+		rh=1+T->right->ht;
+
+	if(lh>rh)
+		return(lh);
+
+	return(rh);
+}
+
+node * rotateright(node *x)
+{
+	node *y;
+	y=x->left;
+	x->left=y->right;
+	y->right=x;
+	x->ht=height(x);
+	y->ht=height(y);
+	return(y);
+}
+
+node * rotateleft(node *x)
+{
+	node *y;
+	y=x->right;
+	x->right=y->left;
+	y->left=x;
+	x->ht=height(x);
+	y->ht=height(y);
+
+	return(y);
+}
+
+node * RR(node *T)
+{
+	T=rotateleft(T);
+	return(T);
+}
+
+node * LL(node *T)
+{
+	T=rotateright(T);
+	return(T);
+}
+
+node * LR(node *T)
+{
+	T->left=rotateleft(T->left);
+	T=rotateright(T);
+
+	return(T);
+}
+
+node * RL(node *T)
+{
+	T->right=rotateright(T->right);
+	T=rotateleft(T);
+	return(T);
+}
+
+int BF(node *T)
+{
+	int lh,rh;
+	if(T==NULL)
+		return(0);
+
+	if(T->left==NULL)
+		lh=0;
+	else
+		lh=1+T->left->ht;
+
+	if(T->right==NULL)
+		rh=0;
+	else
+		rh=1+T->right->ht;
+
+	return(lh-rh);
+}
+
+void preorder(node *T)
+{
+	if(T!=NULL)
+	{
+		printf("%d(Bf=%d)",T->data,BF(T));
+		preorder(T->left);
+		preorder(T->right);
+	}
+}
+
+void inorder(node *T)
+{
+	if(T!=NULL)
+	{
+		inorder(T->left);
+		printf("%d(Bf=%d)",T->data,BF(T));
+		inorder(T->right);
+	}
+}