1 public class BinaryTree<E extends Comparable<E>> { 2 private Node<E> root; 3 4 public BinaryTree (){ 5 root = null; 6 } 7 8 private BinaryTree

Transcription

1 1 public class BinaryTree<E extends Comparable<E>> { 2 private Node<E> root; 3 4 public BinaryTree (){ 5 root = null; 6 } 7 8 private BinaryTree (Node<E> r){ 9 root = r; 10 // null or not is controlled inside of Node<E>. 11 } public BinaryTree (E data, BinaryTree<E> leftt, 14 BinaryTree<E> rightt){ root = new Node<E>(data); 17 if (leftt!=null) 18 root.left = leftt.root; 19 else 20 root.left = null; 21 if (rightt!= null) 22 root.right = rightt.root; 23 else 24 root.right = null; 25 } public String tostring(){ 28 String s = ""; 29 return rec_tostring(root, 1, s); 30 } private String rec_tostring(node<e> node, int depth, String s){ 33 s+=" "; 34 if (node == null) 35 return s+="null\n"; 36 else { 37 String str =""; 38 str = rec_tostring(node.left, depth+1, s); 39 str+=s+""+node.data+"\n"; 40 str += rec_tostring(node.right, depth+1, s); 41 return str; 42 } 43 } public String infixstring(){ 48 String s = ""; 49 return infixtravel(root); 50 } public String prefixstring(){ 53 String s = ""; 54 return prefixtravel(root); 55 } public String postfixstring(){ 58 String s = ""; 59 return postfixtravel(root); 60 } private String infixtravel(node<e> node){ 64 if (node!= null) 65 { 66 String str =""; 67 str = infixtravel(node.left);

2 68 str+= node.data+"\n"; 69 str += infixtravel(node.right); 70 return str; 71 } 72 return ""; 73 } private String prefixtravel(node<e> node){ 76 if (node!= null) { 77 String str =""; 78 str = node.data+"\n"; 79 str += prefixtravel(node.left); 80 str += prefixtravel(node.right); 81 return str; 82 } 83 return ""; 84 } private String postfixtravel(node<e> node){ 87 if (node!= null) { 88 String str =""; 89 str = postfixtravel(node.left); 90 str += postfixtravel(node.right); 91 str+=node.data+"\n"; 92 return str; 93 } 94 else return ""; 95 } public void add(e item){ 99 root = add(root, item); 100 } private Node<E> add(node<e> localroot, E item){ 103 if(localroot == null){ 104 return new Node<E>(item); 105 } 106 else if (item.compareto(localroot.data)<0){ 107 localroot.left = add(localroot.left, item); 108 return localroot; 109 } 110 else if (item.compareto(localroot.data)>0){ 111 localroot.right=add(localroot.right, item); 112 return localroot; 113 } 114 else 115 return localroot; 116 } /* 119 Here is another version of implementation, if 120 the node's new connection will be returned to 121 the parent node public void add(e item){ 124 if (root == null) 125 root = new Node<E> (item); 126 else 127 add(root, item); 128 } private void add(node<e> localroot, E item){ 131 if (item.compareto(localroot.data)<0){ 132 if(localroot.left == null) 133 localroot.left = new Node<E> (item); 134 else

3 135 add(localroot.left, item); 136 } 137 else if (item.compareto(localroot.data)>0){ 138 if(localroot.right == null) 139 localroot.right = new Node<E> (item); 140 else 141 add(localroot.right, item); 142 } 143 } */ public boolean search(e item){ 148 if(root!=null) 149 return search(root, item); 150 else return false; 151 } private boolean search (Node<E> localroot, E item){ 154 int compresult = item.compareto(localroot.data); 155 if (compresult <0) { 156 if(localroot.left!=null) 157 return search(localroot.left, item); 158 else 159 return false; 160 } 161 else if (compresult >0) { 162 if(localroot.right!=null) 163 return search(localroot.right, item); 164 else 165 return false; 166 } 167 else{ 168 return true; 169 } 170 } public void delete(e item){ 173 if (root!=null) 174 root = delete (root, item); 175 } private Node<E> delete (Node<E> localroot, E item){ 180 // search first 181 int compresult = item.compareto(localroot.data); 182 if (compresult <0) { 183 if(localroot.left!=null) 184 localroot.left = delete(localroot.left, item); 185 return localroot; 186 } 187 else if (compresult >0) { 188 if(localroot.right!=null) 189 localroot.right = delete(localroot.right, item); 190 return localroot; 191 } 192 else{ 193 //replacement 194 if(localroot.left == null){ 195 return localroot.right; 196 /* after return, the parent will direct to 197 * this right, either by its left or right 198 * reference 199 */ 200 } 201 else if (localroot.right == null){

4 202 return localroot.left; 203 // see the above for the left null. 204 } 205 else { 206 // hold both children now and need a replacement. 207 // find the maximum from left 208 if (localroot.left.right == null){ 209 localroot.data = localroot.left.data; 210 localroot.left = localroot.left.left; 211 } 212 else 213 localroot.data = findanddeletelargest(localroot.left); return localroot; 216 } 217 } 218 } private E findanddeletelargest(node<e> parent){ 221 if(parent.right.right==null){ 222 E ret = parent.right.data; 223 parent.right = parent.right.left; 224 return ret; 225 } 226 else 227 return findanddeletelargest(parent.right); 228 } public E find_min(){ 231 Node<E> p = root; 232 if (p==null) return null; 233 while(p.left!=null) 234 p = p.left; 235 return p.data; 236 } public E find_max(){ 239 Node<E> p = root; 240 if (p==null) return null; 241 while(p.right!=null) 242 p = p.right; 243 return p.data; 244 } private static class Node<E> { 248 private E data; 249 private Node<E> left; 250 private Node<E> right; private Node(E item){ 255 data = item; 256 left = null; 257 right = null; 258 } private Node(E item, Node<E> refleft, Node<E> refright){ 262 data = item; 263 left = refleft; 264 right = refright; 265 } } 268 //end of private class

5 269 }