Mercurial > hg > Members > shoshi > AADS
view src/tree/AVLTreeMap.java @ 2:36f2373f867b
added AVLTree.java remove operation
author | Shoshi TAMAKI <shoshi@cr.ie.u-ryukyu.ac.jp> |
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date | Wed, 10 Aug 2011 20:14:19 +0900 |
parents | 15920e9b562d |
children | 24613dfbaeab |
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package tree; public class AVLTreeMap<K extends Comparable<K>,V> implements Map<K,V> { private Node<K,V> root; private final Node<K,V> NULL_NODE = new Node<K,V>(null,null,-1,-1,null,null); public static void main(String args[]) { AVLTreeMap<Integer,String> map = new AVLTreeMap<Integer,String>(); map.put(10,"10"); map.put(20,"20"); map.put(30,"30"); map.put(5,"5"); map.put(7,"7"); map.remove(20); } public AVLTreeMap() { root = null; } @Override public void put(K key,V value) { if(root == null){ root = new Node<K,V>(key,value,0,0,NULL_NODE,NULL_NODE); return; } root = _put(root,key,value); } public Node<K,V> _put(Node<K,V> cur,K key,V value) { int result = cur.key.compareTo(key); if(result < 0){ //right if(cur.right == NULL_NODE){ cur.right = new Node<K,V>(key,value,0,0,NULL_NODE,NULL_NODE); cur.rdepth = 1; return cur; } cur.right = _put(cur.right,key,value); cur.rdepth = Math.max(cur.right.ldepth,cur.right.rdepth) + 1; int diff = cur.rdepth - cur.ldepth; if(diff > 1){ //一重回転か二重回転か判断する。 //以下の式は一重回転の場合は rottype が正になるはず。負の場合は二重回転、0の場合はあり得ない。 int rottype = result * cur.right.key.compareTo(key); if(rottype > 0){ return singleRotate(cur,OP_RIGHT); }else{ return doubleRotate(cur,OP_RIGHTLEFT); } } }else if(result > 0){ //left if(cur.left == NULL_NODE){ cur.left = new Node<K,V>(key,value,0,0,NULL_NODE,NULL_NODE); cur.ldepth = 1; return cur; } cur.left = _put(cur.left,key,value); cur.ldepth = Math.max(cur.left.ldepth,cur.left.rdepth) + 1; int diff = cur.ldepth - cur.rdepth; if(diff > 1){ //一重回転か二重回転か判断する。 //以下の式は一重回転の場合は rottype が正になるはず。負の場合は二重回転、0の場合はあり得ない。 int rottype = result * cur.left.key.compareTo(key); if(rottype > 0){ return singleRotate(cur,OP_LEFT); }else{ return doubleRotate(cur,OP_LEFTRIGHT); } } }else{ //find cur.value = value; } return cur; } public V remove(K _key) { RemoveResult<K,V> r = removeTarget(root,_key); root = r.cur; return r.removed.value; } private RemoveResult<K,V> removeTarget(Node<K,V> _cur,K _key) { int result = _cur.key.compareTo(_key); if(result < 0){ //right if(_cur.right == NULL_NODE){ //not found return new RemoveResult<K,V>(_cur,NULL_NODE); } RemoveResult<K,V> r = removeTarget(_cur.right,_key); _cur.right = r.cur; _cur.rdepth = Math.max(_cur.right.ldepth,_cur.right.rdepth) + 1; //要素の削除では,部分木の要素が減ったと考えるのではなく,もう片方の部分木の要素が増えたと考えれば書きやすい int diff = _cur.ldepth - _cur.rdepth; if(diff > 1){ //determine that rotation will be single or double Node<K,V> left = _cur.left; int rottype = left.ldepth - left.rdepth; if(rottype >= 0){ r.cur = singleRotate(_cur,OP_LEFT); }else{ r.cur = doubleRotate(_cur,OP_LEFTRIGHT); } } return r; }else if(result > 0){ //left if(_cur.left == NULL_NODE){ //not found return new RemoveResult<K,V>(_cur,NULL_NODE); } RemoveResult<K,V> r = removeTarget(_cur.right,_key); _cur.left = r.cur; _cur.rdepth = Math.max(_cur.right.ldepth,_cur.right.rdepth) + 1; int diff = _cur.rdepth - _cur.ldepth; if(diff > 1){ //determine that rotation will be single or double Node<K,V> right = _cur.right; int rottype = right.rdepth - right.ldepth; if(rottype >= 0){ r.cur = singleRotate(_cur,OP_RIGHT); }else{ r.cur = doubleRotate(_cur,OP_RIGHTLEFT); } } } //find. //見つかったので,ノードの代わりのノードを検索する. RemoveResult<K,V> r = findNearestNode(_cur.left); if(r != null){ } //見つかった場合は自身を削除対象とする return null; } public RemoveResult<K,V> findNearestNode(Node<K,V> _cur) { if(_cur == NULL_NODE){ return null; } return null; } public static class RemoveResult<K,V> { public Node<K,V> removed; public Node<K,V> cur; public RemoveResult(Node<K,V> _removed,Node<K,V> _cur) { removed = _removed; cur = _cur; } } private static final int OP_LEFT = 1; private static final int OP_RIGHT = 2; public Node<K,V> singleRotate(Node<K,V> target,int type) { switch(type){ case OP_LEFT: Node<K,V> left = target.left; target.left = left.right; left.right = target; target.ldepth = Math.max(target.left.rdepth,target.left.ldepth) + 1; left.rdepth = Math.max(left.right.rdepth,left.right.ldepth) + 1; return left; case OP_RIGHT: Node<K,V> right = target.right; target.right = right.left; right.left = target; target.rdepth = Math.max(target.right.rdepth,target.right.ldepth) + 1; right.ldepth = Math.max(right.left.ldepth,right.left.rdepth) + 1; return right; default: throw new IllegalArgumentException("invalid rotation type"); } } private static final int OP_LEFTRIGHT = 1; private static final int OP_RIGHTLEFT = 2; public Node<K,V> doubleRotate(Node<K,V> target,int type) { switch(type){ case OP_LEFTRIGHT: target.left = singleRotate(target.left,OP_RIGHT); return singleRotate(target,OP_LEFT); case OP_RIGHTLEFT: target.right = singleRotate(target.right,OP_LEFT); return singleRotate(target,OP_RIGHT); default: throw new IllegalArgumentException("invalid rotation type."); } } @Override public V get(K key) { Node<K,V> cur = root; while(cur != NULL_NODE){ int result = cur.key.compareTo(key); if(result < 0){ cur = cur.right; }else if(result > 0){ cur = cur.left; }else{ //find break; } } return cur.value; } private static class Node<K,V> { K key; V value; int rdepth; int ldepth; Node<K,V> left; Node<K,V> right; public Node(K key,V value,int rdepth,int ldepth,Node<K,V> left,Node<K,V> right) { this.right = right; this.left = left; this.ldepth = ldepth; this.rdepth = rdepth; this.key = key; this.value = value; } @Override public String toString() { return "[" + key + ":" + value + "]"; } } }