关于java:数据结构平衡二叉树Java

数据结构—均衡二叉树（Java）

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博客阐明

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阐明

均衡二叉树也叫均衡二叉搜寻树（Self-balancing binary search tree）又被称为 AVL 树，能够保障查问效率较高。
具备以下特点：它是一 棵空树或它的左右两个子树的高度差的绝对值不超过 1，并且左右两个子树都是一棵均衡二叉树。均衡二叉树的罕用实现办法有红黑树、AVL、替罪羊树、Treap、舒展树等。

代码

package cn.guizimo.avl;

public class AVLTree {public static void main(String[] args) {int[] arr = {10, 11, 7, 6, 8, 9};
        AVLTreeDemo avlTree = new AVLTreeDemo();
        for(int i=0; i < arr.length; i++) {avlTree.add(new Node(arr[i]));
        }

        System.out.println("中序遍历");
        avlTree.infixOrder();

        System.out.println("均衡");
        System.out.println("树的高度：" + avlTree.getRoot().height()); //3
        System.out.println("左子树高度：" + avlTree.getRoot().leftHeight()); // 2
        System.out.println("右子树高度" + avlTree.getRoot().rightHeight()); // 2
        System.out.println("根节点：" + avlTree.getRoot());//8
    }
}

class AVLTreeDemo{
    private Node root;

    public Node getRoot() {return root;}

    // 查找以后节点
    public Node search(int value) {if (root == null) {return null;} else {return root.search(value);
        }
    }

    // 找到最小值
    public int delRightTreeMin(Node node) {
        Node target = node;
        while(target.left != null) {target = target.left;}
        delNode(target.value);
        return target.value;
    }

    // 删除节点
    public void delNode(int value) {if (root == null) {return;} else {
            // 删除叶子节点
            Node targetNode = search(value);
            if (targetNode == null) {return;}
            if (root.left == null && root.right == null) {
                root = null;
                return;
            }
            Node parent = searchParent(value);
            if (targetNode.left == null && targetNode.right == null) {if (parent.left != null && parent.left.value == value) {parent.left = null;} else if (parent.right != null && parent.right.value == value) {parent.right = null;}
                // 删除两颗子树的节点
            } else if (targetNode.left != null && targetNode.right != null) {int i = delRightTreeMin(targetNode.right);
                targetNode.value = i;
                // 删除一颗子树的节点
            } else {if (targetNode.left != null) {if (parent != null) {if (parent.left.value == value) {parent.left = targetNode.left;} else {parent.right = targetNode.right;}
                    } else {root = targetNode.left;}
                } else {if (parent != null) {if (parent.left.value == value) {parent.left = targetNode.right;} else if (parent.right.value == value) {parent.right = targetNode.right;}
                    } else {root = targetNode.right;}
                }
            }
        }
    }

    // 查问以后节点的父节点
    public Node searchParent(int value) {if (root == null) {return null;} else {return root.searchParent(value);
        }
    }

    // 增加节点
    public void add(Node node) {if (root == null) {root = node;} else {root.add(node);
        }
    }

    // 中序遍历
    public void infixOrder() {if (root != null) {root.infixOrder();
        } else {System.out.println("");
        }
    }
}

class Node {
    int value;
    Node left;
    Node right;

    public Node(int value) {this.value = value;}

    // 左子树的高度
    public int leftHeight() {if (left == null) {return 0;}
        return left.height();}

    // 右子树的高度
    public int rightHeight() {if (right == null) {return 0;}
        return right.height();}

    // 以后节点的高度
    public int height() {return Math.max(left == null ? 0 : left.height(), right == null ? 0 : right.height()) + 1;
    }

    @Override
    public String toString() {
        return "Node{" +
                "value=" + value +
                '}';
    }

    // 查找节点
    public Node search(int value) {if (value == this.value) {return this;} else if (value < this.value) {if (this.left == null) {return null;}
            return this.left.search(value);
        } else {if (this.right == null) {return null;}
            return this.right.search(value);
        }
    }

    // 查问父节点
    public Node searchParent(int value) {if ((this.left != null && this.left.value == value) ||
                (this.right != null && this.right.value == value)) {return this;} else {if (value < this.value && this.left != null) {return this.left.searchParent(value);
            } else if (value >= this.value && this.right != null) {return this.right.searchParent(value);
            } else {return null;}
        }
    }

    // 增加节点
    public void add(Node node) {if (node == null) {return;}
        if (node.value < this.value) {if (this.left == null) {this.left = node;} else {this.left.add(node);
            }
        } else {if (this.right == null) {this.right = node;} else {this.right.add(node);
            }
        }

        // 左旋转
        if(rightHeight() - leftHeight() > 1) {if(right != null && right.leftHeight() > right.rightHeight()) {right.rightRotate();
                leftRotate();} else {leftRotate();
            }
            return ;
        }

        // 右旋转
        if(leftHeight() - rightHeight() > 1) {if(left != null && left.rightHeight() > left.leftHeight()) {left.leftRotate();
                rightRotate();} else {rightRotate();
            }
        }
    }

    // 中序遍历
    public void infixOrder() {if (this.left != null) {this.left.infixOrder();
        }
        System.out.println(this);
        if (this.right != null) {this.right.infixOrder();
        }
    }

    // 左旋转
    private void leftRotate() {Node newNode = new Node(value);
        newNode.left = left;
        newNode.right = right.left;
        value = right.value;
        right = right.right;
        left = newNode;
    }

    // 右旋转
    private void rightRotate() {Node newNode = new Node(value);
        newNode.right = right;
        newNode.left = left.right;
        value = left.value;
        left = left.left;
        right = newNode;
    }

}

测试

感激

尚硅谷

以及勤奋的本人