Create BinarySearchTree.java

Author: wangzheng0822

java/24_tree/BinarySearchTree.java

@@ -0,0 +1,81 @@
+public class BinarySearchTree {
+ private Node tree;
+
+ public Node find(int data) {
+ Node p = tree;
+ while (p != null) {
+ if (data < p.data) p = p.left;
+ else if (data > p.data) p = p.right;
+ else return p;
+ }
+ return null;
+ }
+ 
+ public void insert(int data) {
+ if (tree == null) {
+ tree = new Node(data);
+ return;
+ }
+
+ Node p = tree;
+ while (p != null) {
+ if (data > p.data) {
+ if (p.right == null) {
+ p.right = new Node(data);
+ return;
+ }
+ p = p.right;
+ } else { // data < p.data
+ if (p.left == null) {
+ p.left = new Node(data);
+ return;
+ }
+ p = p.left;
+ }
+ }
+ }
+
+ public void delete(int data) {
+ Node p = tree; // p指向要删除的节点，初始化指向根节点
+ Node pp = null; // pp记录的是p的父节点
+ while (p != null && p.data != data) {
+ pp = p;
+ if (data > p.data) p = p.right;
+ else p = p.left;
+ }
+ if (p == null) return; // 没有找到
+
+ // 要删除的节点有两个子节点
+ if (p.left != null && p.right != null) { // 查找右子树中最小节点
+ Node minP = p.right;
+ Node minPP = p; // minPP表示minP的父节点
+ while (minP.left != null) {
+ minPP = minP;
+ minP = minP.left;
+ }
+ p.data = minP.data; // 将minP的数据替换到p中
+ p = minP; // 下面就变成了删除minP了
+ pp = minPP;
+ }
+
+ // 删除节点是叶子节点或者仅有一个子节点
+ Node child; // p的子节点
+ if (p.left != null) child = p.left;
+ else if (p.right != null) child = p.right;
+ else child = null;
+
+ if (pp == null) tree = child; // 删除的是根节点
+ else if (pp.left == p) pp.left = child;
+ else pp.right = child;
+ }
+
+ public static class Node {
+ private int data;
+ private Node left;
+ private Node right;
+
+ public Node(int data) {
+ this.data = data;
+ }
+ }
+}