feat: 2286. Booking Concert Tickets in Groups : 线段树

Author: upupming

README.md

@@ -44,6 +44,7 @@
 - [yxc的B站](https://space.bilibili.com/7836741/)
 - [残酷刷题群排行榜](https://wisdompeak.github.io/lc-score-board/)、[残酷刷题群题目清单](https://docs.google.com/spreadsheets/d/1kBGyRsSdbGDu7DzjQcC-UkZjZERdrP8-_QyVGXHSrB8/edit)、[wisdompeak的B站](https://space.bilibili.com/695330558/)
     - [群友YoungForest的博客](https://youngforest.github.io/)
+    - [灵神的模板库 codeforces-go](https://github.com/EndlessCheng/codeforces-go)
     - [群友Bill0412的博客](https://kickstart.best/)
     - [OTTFF的B站](https://space.bilibili.com/97228279/)
     - [zerotrac的B站](https://space.bilibili.com/3203291/)

leetcode/残酷刷题/2286. Booking Concert Tickets in Groups.ts

@@ -0,0 +1,158 @@
+class BookMyShow {
+  // 每一行剩余的座椅数目
+  seats: number[]
+  // 当前仍有座位剩余的最小行号
+  p: number
+  tree: SegmentTree
+  m: number
+  constructor (n: number, m: number) {
+    this.m = m
+    this.seats = Array(n).fill(m)
+    this.p = 0
+    this.tree = new SegmentTree(0, n)
+    // 初始情况，每个节点都有 m 个座位
+    for (let i = 0; i < n; i++) {
+      this.tree.modify(i, m)
+    }
+  }
+
+  gather (k: number, maxRow: number): number[] {
+    let l = 0; let r = maxRow
+    while (l < r) {
+      const mid = l + r >> 1
+      const [max, sum] = this.tree.query(0, mid)
+      if (max >= k) r = mid
+      else l = mid + 1
+    }
+    const [max, sum] = this.tree.query(0, l)
+    if (max < k) return []
+    this.seats[l] -= k
+    // 使用 modify 和 modifyRange 是等价的，modifyRange 更加通用
+    // this.tree.modify(l, this.seats[l])
+    this.tree.modifyRange(l, l, this.seats[l])
+    return [l, this.m - this.seats[l] - k]
+  }
+
+  scatter (k: number, maxRow: number): boolean {
+    const [max, sum] = this.tree.query(0, maxRow)
+    if (sum < k) return false
+    while (k) {
+      const t = Math.min(this.seats[this.p], k)
+      k -= t
+      this.seats[this.p] -= t
+      // this.tree.modify(this.p, this.seats[this.p])
+      this.tree.modifyRange(this.p, this.p, this.seats[this.p])
+      if (this.seats[this.p] === 0) this.p++
+    }
+    return true
+  }
+}
+
+/**
+* Your BookMyShow object will be instantiated and called as such:
+* var obj = new BookMyShow(n, m)
+* var param_1 = obj.gather(k,maxRow)
+* var param_2 = obj.scatter(k,maxRow)
+*/
+
+export declare const a: 1
+
+class Node {
+  start: number
+  end: number
+  max: number = 0
+  sum: number = 0
+  lazy: number | null = null
+  left: null | Node = null
+  right: null | Node = null
+  constructor (start: number, end: number) {
+    this.start = start
+    this.end = end
+  }
+}
+
+// https://www.acwing.com/activity/content/code/content/167900/
+class SegmentTree {
+  root: Node
+  constructor (start: number, end: number) {
+    this.root = new Node(start, end)
+  }
+
+  modify (pos: number, val: number) {
+    this.modifyNode(this.root, pos, val)
+  }
+
+  modifyNode (node: Node, pos: number, val: number) {
+    if (node.start === pos && node.end === pos) {
+      node.max = node.sum = val
+    } else {
+      this.pushdown(node)
+      if (pos <= node.left!.end) this.modifyNode(node.left!, pos, val)
+      if (pos >= node.right!.start) this.modifyNode(node.right!, pos, val)
+      this.pushup(node)
+    }
+  }
+
+  // 使用 modify 和 modifyRange 是等价的，modifyRange 更加通用
+  modifyRange (start: number, end: number, val: number) {
+    this.modifyNodeRange(this.root, start, end, val)
+  }
+
+  modifyNodeRange (node: Node, start: number, end: number, val: number) {
+    if (start <= node.start && end >= node.end) {
+      node.sum = val * (end - start + 1)
+      node.max = val
+      node.lazy = val
+    } else {
+      this.pushdown(node)
+      if (start <= node.left!.end) this.modifyNodeRange(node.left!, start, end, val)
+      if (end >= node.right!.start) this.modifyNodeRange(node.right!, start, end, val)
+      this.pushup(node)
+    }
+  }
+
+  // 这里 pushdown 的作用只是动态创建新节点
+  pushdown (node: Node) {
+    const mid = node.start + node.end >> 1
+    node.left ??= new Node(node.start, mid)
+    node.right ??= new Node(mid + 1, node.end)
+    if (node.lazy != null) {
+      node.left.lazy = node.lazy
+      node.left.max = node.lazy
+      node.left.sum = node.lazy * (node.left.end - node.left.start + 1)
+
+      node.right.lazy = node.lazy
+      node.right.max = node.lazy
+      node.right.sum = node.lazy * (node.right.end - node.right.start + 1)
+
+      node.lazy = null
+    }
+  }
+
+  pushup (node: Node) {
+    node.max = Math.max(node.left!.max, node.right!.max)
+    node.sum = node.left!.sum + node.right!.sum
+  }
+
+  query (start: number, end: number) {
+    return this.queryNode(this.root, start, end)
+  }
+
+  queryNode (node: Node, start: number, end: number) {
+    if (start <= node.start && end >= node.end) return [node.max, node.sum]
+
+    this.pushdown(node)
+    let max = 0; let sum = 0
+    if (start <= node.left!.end) {
+      const [_m, _s] = this.queryNode(node.left!, start, end)
+      max = Math.max(max, _m)
+      sum += _s
+    }
+    if (end >= node.right!.start) {
+      const [_m, _s] = this.queryNode(node.right!, start, end)
+      max = Math.max(max, _m)
+      sum += _s
+    }
+    return [max, sum]
+  }
+}

leetcode/残酷刷题/README.md

@@ -282,6 +282,7 @@
 
 - 715. Range Module
 - 2213. Longest Substring of One Repeating Character
+- 2286. Booking Concert Tickets in Groups
 
 ## Links