Home
Campus Bookshelves
Folsom Lake College
CISP 430: Data Structures (Aljuboori)
5: Trees
5.6: Example extract of Java code for binary tree delete operation

5.6: Example extract of Java code for binary tree delete operation

Last updated
Save as PDF

Page ID: 47905

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

private Treap1<K, V>.TreapNode deleteNode(K k, Treap1<K, V>.TreapNode node, Deleted del) {
 
		if (node == null) {
			return null;
		} else if (k.compareTo(node.k) < 0) {
			 node.left = (k, node.left, del) ;
		} else if (k.compareTo(node.k) > 0) {
			node.right = deleteNode(k, node.right, del);
 
			// k.compareTo(node.k) == 0
		} else if ( node.left == null ) {
				del.success = true;
				return node.right;
		} else if ( node.right == null) {
			  del.success = true;
				return node.left;
		} else if (node.left !=null && node.right != null){
		/*
        // non-standard method,
		// left rotate and all delete on left subtree

			TreapNode tmp = node.right;
			node.right = node.right.left;
		    tmp.left = node;
		    node = tmp;			
			node.left = deleteNode(k , node.left, del);
			
         */

	    // more standard method ? doesn't disturb tree structure as much
	    // find leftmost descendant of the right child node and replace contents

			TreapNode n2 = node.right;
			TreapNode previous2 = null;
			while (n2.left != null) {
				previous2 = n2;
				n2 = n2.left;
			}
 
			if (previous2 != null) {
				previous2.left = n2.right;
                //n2 has no parent link, orphaned
			} else {
				node.right = n2.right;
                //n2 has no parent link, orphaned
			}
 
			node.k = n2.k;
			node.val = n2.val;
			del.success = true;
            // once n2 out of scope, the orphaned node at n2 will be garbage collected, 
		}
 
		return node;
	}