引入红黑树近似查询

include/RedBlackTree.h

@@ -103,6 +103,8 @@ namespace ling {
         /// 查找元素
         Node *iterativeSearch(Node *x, T key) const;
 
+        Node *findSearch(Node *x, T key) const;
+
         /// 删除元素
         void remove(Node *&root, Node *node);
 
@@ -126,9 +128,12 @@ namespace ling {
         /// 删除节点
         void remove(T key);
 
-        /// 查找节点
+        /// 查找元素
+        /// 区别于findSearch，此方法会在没有匹配时返回接近的节点
         Node *iterativeSearch(T key);
 
+        Node *findSearch(T key);
+
         /// 根节点
         Node *getRoot() {
             return rootNode;
@@ -332,6 +337,24 @@ namespace ling {
 
     template<typename T>
     typename RedBlackTree<T>::Node *RedBlackTree<T>::iterativeSearch(RedBlackTree::Node *x, T key) const {
+        Relation temp;
+        Node *closest = nullptr;
+        while (x != nullptr) {
+            temp = equal(x->value, key);
+            if (temp == EQUAL)
+                return x;
+            if (temp == SMALL) {
+                closest = x;
+                x = x->right;
+            } else {
+                x = x->left;
+            }
+        }
+        return closest;
+    }
+
+    template<typename T>
+    typename RedBlackTree<T>::Node *RedBlackTree<T>::findSearch(RedBlackTree::Node *x, T key) const {
         while ((x != nullptr) && equal(x->value, key) != EQUAL) {
             if (equal(key, x->value) == SMALL) {
                 x = x->left;
@@ -342,6 +365,11 @@ namespace ling {
         return x;
     }
 
+    template<typename T>
+    typename RedBlackTree<T>::Node *RedBlackTree<T>::findSearch(T key) {
+        return findSearch(rootNode, key);
+    }
+
     template<typename T>
     typename RedBlackTree<T>::Node *RedBlackTree<T>::iterativeSearch(T key) {
         return iterativeSearch(rootNode, key);