二叉搜索树的基本操作
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二叉搜索树插入元素
/**
* user：ypc；
* date：2021-05-18;
* time: 15:09;
*/
class Node {
int val;
Node left;
Node right;
Node(int val) {
this.val = val;
}
}
public void insert(int key) {
Node node = new Node(key);
if (this.root == null) {
root = node;
}
Node cur = root;
Node parent = null;
while (cur != null) {
if (cur.val == key) {
//System.out.println("元素已经存在");
return;
} else if (cur.val > key) {
parent = cur;
cur = cur.left;
} else {
parent = cur;
cur = cur.right;
}
}
if (key > parent.val) {
parent.right = node;
} else {
parent.left = node;
}
}
搜索指定节点
public boolean search(int key) {
Node cur = root;
while (cur != null) {
if (cur.val == key) {
return true;
} else if (cur.val > key) {
cur = cur.left;
} else {
cur = cur.right;
}
}
return false;
}
删除节点方式一
public void removenode1(Node parent, Node cur) {
if (cur.left == null) {
if (cur == root) {
root = cur.right;
} else if (cur == parent.right) {
parent.left = cur.right;
} else {
parent.right = cur.right;
}
} else if (cur.right == null) {
if (cur == root) {
root.left = cur;
} else if (cur == parent.right) {
parent.right = cur.left;
} else {
parent.left = cur.left;
}
} else {
Node tp = cur;
Node t = cur.right;
while (t.left != null) {
tp = t;
t = t.left;
}
if (tp.left == t) {
cur.val = t.val;
tp.left = t.right;
}
if (tp.right == t) {
cur.val = t.val;
tp.right = t.right;
}
}
}
public void remove(int key) {
Node cur = root;
Node parent = null;
while (cur != null) {
if (cur.val == key) {
removenode1(parent, cur);
//removenode2(parent, cur);
return;
} else if (key > cur.val) {
parent = cur;
cur = cur.right;
} else {
parent = cur;
cur = cur.left;
}
}
}
删除节点方式二
public void removenode2(Node parent, Node cur) {
if (cur.left == null) {
if (cur == root) {
root = cur.right;
} else if (cur == parent.right) {
parent.left = cur.right;
} else {
parent.right = cur.right;
}
} else if (cur.right == null) {
if (cur == root) {
root.left = cur;
} else if (cur == parent.right) {
parent.right = cur.left;
} else {
parent.left = cur.left;
}
} else {
Node tp = cur;
Node t = cur.left;
while (t.right != null) {
tp = t;
t = t.right;
}
if (tp.right == t) {
cur.val = t.val;
tp.right = t.left;
}
if (tp.left == t) {
cur.val = t.val;
tp.left = t.left;
}
}
}
运行结果
/**
* user：ypc；
* date：2021-05-18;
* time: 15:09;
*/
class TestBinarySearchTree {
public static void main(String[] args) {
int a[] = {5, 3, 4, 1, 7, 8, 2, 6, 0, 9};
BinarySearchTree binarySearchTree = new BinarySearchTree();
for (int i = 0; i < a.length; i++) {
binarySearchTree.insert(a[i]);
}
binarySearchTree.inOrderTree(binarySearchTree.root);
System.out.println();
binarySearchTree.preOrderTree(binarySearchTree.root);
binarySearchTree.remove(7);
System.out.println();
System.out.println("方法一删除后");
binarySearchTree.inOrderTree(binarySearchTree.root);
System.out.println();
binarySearchTree.preOrderTree(binarySearchTree.root);
}
}
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