标签:红黑树
红黑树是一棵二叉搜索树,它在每个节点上增加了一个存储位来表示节点的颜色,可以是Red或Black。通过对任何一条从根到叶子简单路径上的颜色来约束,红黑树保证最长路径不超过最短路径的两倍,因而近似于平衡。
红黑树是满足下面红黑性质的二叉搜索树:
(1)每个节点,不是红色就是黑色的。
(2)根节点是黑色的。
(3)如果一个节点是红色的,则它的两个子节点是黑色的(没有连续的红节点)。
(4)对每个节点,从该节点到其所有后代叶节点的简单路径上,均包含相同数目的黑色节点。(每条路径的黑色节点的数量相等)
(5)每个空节点都是黑色的。
插入的几种情况
ps:cur为当前节点,p为父节点,g为祖父节点,u为叔叔节点。
(1)第一种情况
cur为红,p为红,g为黑,u存在且为红。
则将p,u改为黑,g改为红,然后把g当成cur,继续向上调整。
(2)第二种情况
cur为红,p为红,g为黑,u不存在/u为黑。
p为g的左孩子,cur为p的左孩子,则进行右单旋。
转;相反,p为g的右孩子,cur为p的右孩子,则进 行左单旋转。p、g变色--p变黑,g变红。
(3)第三种情况
cur为红,p为红,g为黑,u不存在/u为黑。
p为g的左孩子,cur为p的右孩子,则针对p做左单旋转;相反,p为g的右孩子,cur为p的左孩子,则针对p做右单旋转,则转换成了情况2。
代码实现:
#include<iostream> using namespace std; enum Color { RED, BLACK }; template<class K,class V> struct RBTreeNode{ RBTreeNode<K, V>* _left; RBTreeNode<K, V>* _right; RBTreeNode<K, V>* _parent; K _key; V _value; Color _col; //节点的颜色 RBTreeNode(const K& key, const V& value) :_left(NULL) , _right(NULL) , _parent(NULL) , _key(key) , _value(value) , _col(RED) {} }; template<class K,class V> class RBTree{ typedef RBTreeNode<K, V> Node; public: RBTree() :_root(NULL) {} bool Insert(const K& key, const V& value) { if (_root == NULL) { _root = new Node(key,value); _root->_col = BLACK; return true; } Node* cur = _root; Node* parent = NULL; while (cur) { if (cur->_key > key) { parent = cur; cur = cur->_left; } else if (cur->_key < key) { parent = cur; cur = cur->_right; } else { return false; } } cur = new Node(key, value); if (parent->_key > key) { parent->_left = cur; cur->_parent = parent; } else { parent->_right = cur; cur->_parent = parent; } while (cur != _root&&parent->_col == RED) { Node* grandfather = parent->_parent; if (parent == grandfather->_left) { Node* uncle = grandfather->_right; //第1种情况 if (uncle&&uncle->_col == RED) { parent->_col = uncle->_col = BLACK; grandfather->_col = RED; //继续向上调整 cur = grandfather; parent = cur->_parent; } else { //第3种情况转换成第2种情况 if (cur == parent->_right) { _RotateL(parent); swap(parent,cur); } //第2种情况 _RotateR(grandfather); parent->_col = BLACK; grandfather->_col = RED; break; } } else //parent=grandfather->_right { Node* uncle = grandfather->_left; //第1种情况 if (uncle&&uncle->_col == RED) { parent->_col = uncle->_col = BLACK; grandfather->_col = RED; //向上继续调整 cur = grandfather; parent = cur->_parent; } else { //第3种情况 if (cur == parent->_left) { _RotateR(parent); swap(parent,cur); } //第2种情况 _RotateL(grandfather); grandfather->_col = RED; parent->_col = BLACK; break; } } } _root->_col = BLACK; return true; } Node* Find(const K& key) { if (_root == NULL) return NULL; Node* cur = _root; while (cur) { if (cur->_key > key) cur = cur->_left; else if (cur->_key < key) cur = cur->_right; else return cur; } return NULL; } void InOrder() { _InOrder(_root); cout << endl; } bool IsBlance() { if (_root == NULL) return true; if (_root->_col == RED) return false; int k = 0; Node* cur = _root; while (cur) { if (cur->_col == BLACK) ++k; cur = cur->_left; } int count = 0; return _IsBlance(_root,k,count); } protected: void _RotateR(Node* parent) { Node* subL = parent->_left; Node* subLR = subL->_right; parent->_left = subLR; if (subLR) subLR->_parent = parent; subL->_right = parent; Node* ppNode = parent->_parent; parent->_parent = subL; if (ppNode == NULL) { _root = subL; subL->_parent = NULL; } else { if (ppNode->_left == parent) { ppNode->_left = subL; subL->_parent = ppNode; } else { ppNode->_right = subL; subL->_parent = ppNode; } } } void _RotateL(Node* parent) { Node* subR = parent->_right; Node* subRL = subR->_left; parent->_right = subRL; if (subRL) subRL->_parent = parent; subR->_left = parent; Node* ppNode = parent->_parent; parent->_parent = subR; if (ppNode == NULL) { _root = subR; subR->_parent = NULL; } else { if (ppNode->_left == parent) { ppNode->_left = subR; subR->_parent = ppNode; } else { ppNode->_right = subR; subR->_parent = ppNode; } } } void _InOrder(Node* root) { if (root == NULL) { return; } _InOrder(root->_left); cout << root->_key << " "; _InOrder(root->_right); } bool _IsBlance(Node* root, const int k, int count) { if (root == NULL) return true; //规则3:没有连续的红节点 if (root->_col == RED&&root->_parent->_col == RED) { cout << "出现连续的红色节点" << root->_key<<endl; return false; } if (root->_col == BLACK) ++count; //规则4:每条路径的黑色节点的数量相等 if (root->_left == NULL&&root->_right == NULL&&count != k) { cout << "黑色节点个数不相等" << root->_key<<endl; return false; } return _IsBlance(root->_left, k, count) && _IsBlance(root->_right, k, count); } protected: Node* _root; }; #include "RBTree.h" void Test1() { int a[] ={16, 3, 7, 11, 9, 26, 18, 14, 15}; RBTree<int, int> rbt; for (int i = 0; i < sizeof(a) / sizeof(a[0]); ++i) { rbt.Insert(a[i],i); } rbt.InOrder(); cout << rbt.IsBlance() << endl; RBTreeNode<int, int>* ret1=rbt.Find(15); if (ret1) { cout << ret1->_key << ":" << ret1->_value << endl; } else { cout << "没有找到ret1" << endl; } RBTreeNode<int, int>* ret2 = rbt.Find(8); if (ret2) { cout << ret2->_key << ":" << ret2->_value << endl; } else { cout << "没有找到ret2" << endl; } } int main() { Test1(); return 0; }
运行结果:
本文出自 “zwy” 博客,请务必保留此出处http://10548195.blog.51cto.com/10538195/1829211
标签:红黑树
原文地址:http://10548195.blog.51cto.com/10538195/1829211