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LCP 52. 二叉搜索树染色

题目描述

欢迎各位勇者来到力扣城,本次试炼主题为「二叉搜索树染色」。

每位勇士面前设有一个二叉搜索树的模型,模型的根节点为 root,树上的各个节点值均不重复。初始时,所有节点均为蓝色。现在按顺序对这棵二叉树进行若干次操作, ops[i] = [type, x, y] 表示第 i 次操作为:

  • type 等于 0 时,将节点值范围在 [x, y] 的节点均染蓝
  • type 等于 1 时,将节点值范围在 [x, y] 的节点均染红

请返回完成所有染色后,该二叉树中红色节点的数量。

注意:

  • 题目保证对于每个操作的 xy 值定出现在二叉搜索树节点中

示例 1:

输入:root = [1,null,2,null,3,null,4,null,5], ops = [[1,2,4],[1,1,3],[0,3,5]]

输出:2

解释: 第 0 次操作,将值为 2、3、4 的节点染红; 第 1 次操作,将值为 1、2、3 的节点染红; 第 2 次操作,将值为 3、4、5 的节点染蓝; 因此,最终值为 1、2 的节点为红色节点,返回数量 2 image.png

示例 2:

输入:root = [4,2,7,1,null,5,null,null,null,null,6] > ops = [[0,2,2],[1,1,5],[0,4,5],[1,5,7]]

输出:5

解释: 第 0 次操作,将值为 2 的节点染蓝; 第 1 次操作,将值为 1、2、4、5 的节点染红; 第 2 次操作,将值为 4、5 的节点染蓝; 第 3 次操作,将值为 5、6、7 的节点染红; 因此,最终值为 1、2、5、6、7 的节点为红色节点,返回数量 5 image.png

提示:

  • 1 <= 二叉树节点数量 <= 10^5
  • 1 <= ops.length <= 10^5
  • ops[i].length == 3
  • ops[i][0] 仅为 0 or 1
  • 0 <= ops[i][1] <= ops[i][2] <= 10^9
  • 0 <= 节点值 <= 10^9

解法

方法一:有序集合 + 倒序遍历

我们先遍历一遍二叉树,将所有节点的值加入到有序集合中。

接下来,由于节点的染色状态只跟最后一个操作有关,因此,我们可以倒序遍历操作数组。对于每个操作 \((t, x, y)\),我们在有序集合中找到所有值在 \([x, y]\) 范围内的节点,将其从有序集合中删除。如果 \(t = 1\),说明这些节点被染成了红色,我们将其数量累加到答案种。

最后,我们返回答案。

时间复杂度 \(O(m + n \times \log n)\),空间复杂度 \(O(n)\)。其中 \(m\)\(n\) 分别是操作数组的长度和二叉树的节点数量。

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# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def getNumber(self, root: Optional[TreeNode], ops: List[List[int]]) -> int:
        def dfs(root):
            if root is None:
                return
            sl.add(root.val)
            dfs(root.left)
            dfs(root.right)

        sl = SortedList()
        dfs(root)
        ans = 0
        for t, x, y in ops[::-1]:
            i = sl.bisect_left(x)
            while i < len(sl) and sl[i] <= y:
                sl.pop(i)
                ans += t == 1
        return ans
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/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    private TreeSet<Integer> ts = new TreeSet<>();

    public int getNumber(TreeNode root, int[][] ops) {
        dfs(root);
        int ans = 0;
        for (int i = ops.length - 1; i >= 0; --i) {
            int t = ops[i][0];
            int x = ops[i][1], y = ops[i][2];
            Integer ceiling = ts.ceiling(x);
            while (ceiling != null && ceiling <= y) {
                ts.remove(ceiling);
                ceiling = ts.ceiling(x);
                ans += t;
            }
        }
        return ans;
    }

    private void dfs(TreeNode root) {
        if (root == null) {
            return;
        }
        ts.add(root.val);
        dfs(root.left);
        dfs(root.right);
    }
}
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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int getNumber(TreeNode* root, vector<vector<int>>& ops) {
        set<int> ts;
        function<void(TreeNode*)> dfs = [&](TreeNode* root) {
            if (root == nullptr) {
                return;
            }
            ts.insert(root->val);
            dfs(root->left);
            dfs(root->right);
        };
        dfs(root);
        int ans = 0;
        for (int i = ops.size() - 1; ~i; --i) {
            int t = ops[i][0];
            int x = ops[i][1], y = ops[i][2];
            auto it = ts.lower_bound(x);
            while (it != ts.end() && *it <= y) {
                ts.erase(it++);
                ans += t;
            }
        }
        return ans;
    }
};
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/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func getNumber(root *TreeNode, ops [][]int) (ans int) {
    rbt := redblacktree.NewWithIntComparator()
    var dfs func(root *TreeNode)
    dfs = func(root *TreeNode) {
        if root == nil {
            return
        }
        rbt.Put(root.Val, nil)
        dfs(root.Left)
        dfs(root.Right)
    }
    dfs(root)
    for i := len(ops) - 1; i >= 0; i-- {
        t, x, y := ops[i][0], ops[i][1], ops[i][2]
        node, _ := rbt.Ceiling(x)
        for node != nil && node.Key.(int) <= y {
            rbt.Remove(node.Key)
            node, _ = rbt.Ceiling(x)
            ans += t
        }
    }
    return
}
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/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

function getNumber(root: TreeNode | null, ops: number[][]): number {
    const ts = new TreeSet<number>();
    const dfs = (node: TreeNode | null) => {
        if (!node) {
            return;
        }
        ts.add(node.val);
        dfs(node.left);
        dfs(node.right);
    };
    dfs(root);
    let ans = 0;
    for (let i = ops.length - 1; ~i; --i) {
        const [t, x, y] = ops[i];
        let ceiling = ts.ceil(x);
        while (ceiling !== null && ceiling <= y) {
            ts.delete(ceiling);
            ceiling = ts.ceil(x);
            ans += t;
        }
    }
    return ans;
}

type Compare<T> = (lhs: T, rhs: T) => number;

class RBTreeNode<T = number> {
    data: T;
    count: number;
    left: RBTreeNode<T> | null;
    right: RBTreeNode<T> | null;
    parent: RBTreeNode<T> | null;
    color: number;
    constructor(data: T) {
        this.data = data;
        this.left = this.right = this.parent = null;
        this.color = 0;
        this.count = 1;
    }

    sibling(): RBTreeNode<T> | null {
        if (!this.parent) return null; // sibling null if no parent
        return this.isOnLeft() ? this.parent.right : this.parent.left;
    }

    isOnLeft(): boolean {
        return this === this.parent!.left;
    }

    hasRedChild(): boolean {
        return (
            Boolean(this.left && this.left.color === 0) ||
            Boolean(this.right && this.right.color === 0)
        );
    }
}

class RBTree<T> {
    root: RBTreeNode<T> | null;
    lt: (l: T, r: T) => boolean;
    constructor(compare: Compare<T> = (l: T, r: T) => (l < r ? -1 : l > r ? 1 : 0)) {
        this.root = null;
        this.lt = (l: T, r: T) => compare(l, r) < 0;
    }

    rotateLeft(pt: RBTreeNode<T>): void {
        const right = pt.right!;
        pt.right = right.left;

        if (pt.right) pt.right.parent = pt;
        right.parent = pt.parent;

        if (!pt.parent) this.root = right;
        else if (pt === pt.parent.left) pt.parent.left = right;
        else pt.parent.right = right;

        right.left = pt;
        pt.parent = right;
    }

    rotateRight(pt: RBTreeNode<T>): void {
        const left = pt.left!;
        pt.left = left.right;

        if (pt.left) pt.left.parent = pt;
        left.parent = pt.parent;

        if (!pt.parent) this.root = left;
        else if (pt === pt.parent.left) pt.parent.left = left;
        else pt.parent.right = left;

        left.right = pt;
        pt.parent = left;
    }

    swapColor(p1: RBTreeNode<T>, p2: RBTreeNode<T>): void {
        const tmp = p1.color;
        p1.color = p2.color;
        p2.color = tmp;
    }

    swapData(p1: RBTreeNode<T>, p2: RBTreeNode<T>): void {
        const tmp = p1.data;
        p1.data = p2.data;
        p2.data = tmp;
    }

    fixAfterInsert(pt: RBTreeNode<T>): void {
        let parent = null;
        let grandParent = null;

        while (pt !== this.root && pt.color !== 1 && pt.parent?.color === 0) {
            parent = pt.parent;
            grandParent = pt.parent.parent;

            /*  Case : A
                Parent of pt is left child of Grand-parent of pt */
            if (parent === grandParent?.left) {
                const uncle = grandParent.right;

                /* Case : 1
                   The uncle of pt is also red
                   Only Recoloring required */
                if (uncle && uncle.color === 0) {
                    grandParent.color = 0;
                    parent.color = 1;
                    uncle.color = 1;
                    pt = grandParent;
                } else {
                    /* Case : 2
                       pt is right child of its parent
                       Left-rotation required */
                    if (pt === parent.right) {
                        this.rotateLeft(parent);
                        pt = parent;
                        parent = pt.parent;
                    }

                    /* Case : 3
                       pt is left child of its parent
                       Right-rotation required */
                    this.rotateRight(grandParent);
                    this.swapColor(parent!, grandParent);
                    pt = parent!;
                }
            } else {
                /* Case : B
               Parent of pt is right child of Grand-parent of pt */
                const uncle = grandParent!.left;

                /*  Case : 1
                    The uncle of pt is also red
                    Only Recoloring required */
                if (uncle != null && uncle.color === 0) {
                    grandParent!.color = 0;
                    parent.color = 1;
                    uncle.color = 1;
                    pt = grandParent!;
                } else {
                    /* Case : 2
                       pt is left child of its parent
                       Right-rotation required */
                    if (pt === parent.left) {
                        this.rotateRight(parent);
                        pt = parent;
                        parent = pt.parent;
                    }

                    /* Case : 3
                       pt is right child of its parent
                       Left-rotation required */
                    this.rotateLeft(grandParent!);
                    this.swapColor(parent!, grandParent!);
                    pt = parent!;
                }
            }
        }
        this.root!.color = 1;
    }

    delete(val: T): boolean {
        const node = this.find(val);
        if (!node) return false;
        node.count--;
        if (!node.count) this.deleteNode(node);
        return true;
    }

    deleteAll(val: T): boolean {
        const node = this.find(val);
        if (!node) return false;
        this.deleteNode(node);
        return true;
    }

    deleteNode(v: RBTreeNode<T>): void {
        const u = BSTreplace(v);

        // True when u and v are both black
        const uvBlack = (u === null || u.color === 1) && v.color === 1;
        const parent = v.parent!;

        if (!u) {
            // u is null therefore v is leaf
            if (v === this.root) this.root = null;
            // v is root, making root null
            else {
                if (uvBlack) {
                    // u and v both black
                    // v is leaf, fix double black at v
                    this.fixDoubleBlack(v);
                } else {
                    // u or v is red
                    if (v.sibling()) {
                        // sibling is not null, make it red"
                        v.sibling()!.color = 0;
                    }
                }
                // delete v from the tree
                if (v.isOnLeft()) parent.left = null;
                else parent.right = null;
            }
            return;
        }

        if (!v.left || !v.right) {
            // v has 1 child
            if (v === this.root) {
                // v is root, assign the value of u to v, and delete u
                v.data = u.data;
                v.left = v.right = null;
            } else {
                // Detach v from tree and move u up
                if (v.isOnLeft()) parent.left = u;
                else parent.right = u;
                u.parent = parent;
                if (uvBlack) this.fixDoubleBlack(u);
                // u and v both black, fix double black at u
                else u.color = 1; // u or v red, color u black
            }
            return;
        }

        // v has 2 children, swap data with successor and recurse
        this.swapData(u, v);
        this.deleteNode(u);

        // find node that replaces a deleted node in BST
        function BSTreplace(x: RBTreeNode<T>): RBTreeNode<T> | null {
            // when node have 2 children
            if (x.left && x.right) return successor(x.right);
            // when leaf
            if (!x.left && !x.right) return null;
            // when single child
            return x.left ?? x.right;
        }
        // find node that do not have a left child
        // in the subtree of the given node
        function successor(x: RBTreeNode<T>): RBTreeNode<T> {
            let temp = x;
            while (temp.left) temp = temp.left;
            return temp;
        }
    }

    fixDoubleBlack(x: RBTreeNode<T>): void {
        if (x === this.root) return; // Reached root

        const sibling = x.sibling();
        const parent = x.parent!;
        if (!sibling) {
            // No sibiling, double black pushed up
            this.fixDoubleBlack(parent);
        } else {
            if (sibling.color === 0) {
                // Sibling red
                parent.color = 0;
                sibling.color = 1;
                if (sibling.isOnLeft()) this.rotateRight(parent);
                // left case
                else this.rotateLeft(parent); // right case
                this.fixDoubleBlack(x);
            } else {
                // Sibling black
                if (sibling.hasRedChild()) {
                    // at least 1 red children
                    if (sibling.left && sibling.left.color === 0) {
                        if (sibling.isOnLeft()) {
                            // left left
                            sibling.left.color = sibling.color;
                            sibling.color = parent.color;
                            this.rotateRight(parent);
                        } else {
                            // right left
                            sibling.left.color = parent.color;
                            this.rotateRight(sibling);
                            this.rotateLeft(parent);
                        }
                    } else {
                        if (sibling.isOnLeft()) {
                            // left right
                            sibling.right!.color = parent.color;
                            this.rotateLeft(sibling);
                            this.rotateRight(parent);
                        } else {
                            // right right
                            sibling.right!.color = sibling.color;
                            sibling.color = parent.color;
                            this.rotateLeft(parent);
                        }
                    }
                    parent.color = 1;
                } else {
                    // 2 black children
                    sibling.color = 0;
                    if (parent.color === 1) this.fixDoubleBlack(parent);
                    else parent.color = 1;
                }
            }
        }
    }

    insert(data: T): boolean {
        // search for a position to insert
        let parent = this.root;
        while (parent) {
            if (this.lt(data, parent.data)) {
                if (!parent.left) break;
                else parent = parent.left;
            } else if (this.lt(parent.data, data)) {
                if (!parent.right) break;
                else parent = parent.right;
            } else break;
        }

        // insert node into parent
        const node = new RBTreeNode(data);
        if (!parent) this.root = node;
        else if (this.lt(node.data, parent.data)) parent.left = node;
        else if (this.lt(parent.data, node.data)) parent.right = node;
        else {
            parent.count++;
            return false;
        }
        node.parent = parent;
        this.fixAfterInsert(node);
        return true;
    }

    find(data: T): RBTreeNode<T> | null {
        let p = this.root;
        while (p) {
            if (this.lt(data, p.data)) {
                p = p.left;
            } else if (this.lt(p.data, data)) {
                p = p.right;
            } else break;
        }
        return p ?? null;
    }

    *inOrder(root: RBTreeNode<T> = this.root!): Generator<T, undefined, void> {
        if (!root) return;
        for (const v of this.inOrder(root.left!)) yield v;
        yield root.data;
        for (const v of this.inOrder(root.right!)) yield v;
    }

    *reverseInOrder(root: RBTreeNode<T> = this.root!): Generator<T, undefined, void> {
        if (!root) return;
        for (const v of this.reverseInOrder(root.right!)) yield v;
        yield root.data;
        for (const v of this.reverseInOrder(root.left!)) yield v;
    }
}

class TreeSet<T = number> {
    _size: number;
    tree: RBTree<T>;
    compare: Compare<T>;
    constructor(
        collection: T[] | Compare<T> = [],
        compare: Compare<T> = (l: T, r: T) => (l < r ? -1 : l > r ? 1 : 0),
    ) {
        if (typeof collection === 'function') {
            compare = collection;
            collection = [];
        }
        this._size = 0;
        this.compare = compare;
        this.tree = new RBTree(compare);
        for (const val of collection) this.add(val);
    }

    size(): number {
        return this._size;
    }

    has(val: T): boolean {
        return !!this.tree.find(val);
    }

    add(val: T): boolean {
        const successful = this.tree.insert(val);
        this._size += successful ? 1 : 0;
        return successful;
    }

    delete(val: T): boolean {
        const deleted = this.tree.deleteAll(val);
        this._size -= deleted ? 1 : 0;
        return deleted;
    }

    ceil(val: T): T | undefined {
        let p = this.tree.root;
        let higher = null;
        while (p) {
            if (this.compare(p.data, val) >= 0) {
                higher = p;
                p = p.left;
            } else {
                p = p.right;
            }
        }
        return higher?.data;
    }

    floor(val: T): T | undefined {
        let p = this.tree.root;
        let lower = null;
        while (p) {
            if (this.compare(val, p.data) >= 0) {
                lower = p;
                p = p.right;
            } else {
                p = p.left;
            }
        }
        return lower?.data;
    }

    higher(val: T): T | undefined {
        let p = this.tree.root;
        let higher = null;
        while (p) {
            if (this.compare(val, p.data) < 0) {
                higher = p;
                p = p.left;
            } else {
                p = p.right;
            }
        }
        return higher?.data;
    }

    lower(val: T): T | undefined {
        let p = this.tree.root;
        let lower = null;
        while (p) {
            if (this.compare(p.data, val) < 0) {
                lower = p;
                p = p.right;
            } else {
                p = p.left;
            }
        }
        return lower?.data;
    }

    first(): T | undefined {
        return this.tree.inOrder().next().value;
    }

    last(): T | undefined {
        return this.tree.reverseInOrder().next().value;
    }

    shift(): T | undefined {
        const first = this.first();
        if (first === undefined) return undefined;
        this.delete(first);
        return first;
    }

    pop(): T | undefined {
        const last = this.last();
        if (last === undefined) return undefined;
        this.delete(last);
        return last;
    }

    *[Symbol.iterator](): Generator<T, void, void> {
        for (const val of this.values()) yield val;
    }

    *keys(): Generator<T, void, void> {
        for (const val of this.values()) yield val;
    }

    *values(): Generator<T, undefined, void> {
        for (const val of this.tree.inOrder()) yield val;
        return undefined;
    }

    /**
     * Return a generator for reverse order traversing the set
     */
    *rvalues(): Generator<T, undefined, void> {
        for (const val of this.tree.reverseInOrder()) yield val;
        return undefined;
    }
}
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/* public class TreeNode {
*     public var val: Int
*     public var left: TreeNode?
*     public var right: TreeNode?
*     public init() { self.val = 0; self.left = nil; self.right = nil; }
*     public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
*     public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
*         self.val = val
*         self.left = left
*         self.right = right
*     }
* }
*/

class Solution {
    private var treeValues: [Int] = []

    func getNumber(_ root: TreeNode?, _ ops: [[Int]]) -> Int {
        collectValues(root)

        treeValues.sort()

        var ans = 0
        for op in ops.reversed() {
            let t = op[0]
            let x = op[1]
            let y = op[2]
            var indicesToRemove: [Int] = []

            for i in 0..<treeValues.count {
                let val = treeValues[i]
                if val >= x && val <= y {
                    indicesToRemove.append(i)
                    ans += t
                }
            }

            for index in indicesToRemove.reversed() {
                treeValues.remove(at: index)
            }
        }

        return ans
    }

    private func collectValues(_ root: TreeNode?) {
        guard let root = root else { return }
        treeValues.append(root.val)
        collectValues(root.left)
        collectValues(root.right)
    }
}

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