【第一个线段树+第一个Java程序！】hdoj 1754 I Hate It

最新推荐文章于 2025-03-04 21:30:22 发布

原创最新推荐文章于 2025-03-04 21:30:22 发布 · 2.5k 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#java #tree #query #build #class #cmd

ACM/ICPC 专栏收录该内容

100 篇文章

订阅专栏

本文介绍了一种基于区间树的数据结构实现，用于高效地完成区间查询和更新操作。该实现适用于处理大规模数据集，特别是在需要频繁进行区间最大值查询及单点更新的应用场景中表现优秀。文中提供了完整的Java和C++代码示例，详细展示了如何构建区间树并执行查询与更新操作。

Java代码。。。。。纠结了好久。。。。

import java.io.*; import java.util.*; class Tree { public Tree L, R; public int ValueL, ValueR; public int maxscore; }; public class Main { static int score[] = new int[200010]; public static void main(String[] args) throws IOException { class IntervalTree { public int pos; public Tree nodes[] = new Tree[400010]; public IntervalTree() { for (int j = 0; j < 400010; j++) { nodes[j] = new Tree(); } } public Tree Build(int L, int R) { Tree rootTree = nodes[pos++]; rootTree.ValueL = L; rootTree.ValueR = R; if (L == R) { rootTree.maxscore = Math.max(score[L], score[R]); return rootTree; } else { int mid; mid = (L+R)/2; rootTree.L = Build(L, mid); rootTree.R = Build(mid+1, R); rootTree.maxscore = Math.max(rootTree.L.maxscore, rootTree.R.maxscore); } return rootTree; } public int Query(Tree root, int LL, int RR) { int ret = 0; if (LL == root.ValueL && RR == root.ValueR) { return root.maxscore; } else { int mid; mid = (root.ValueL+root.ValueR)/2; if (RR <= mid) ret = Query(root.L, LL, RR); else if (LL > mid) ret = Query(root.R, LL, RR); else ret = Math.max(Query(root.L, LL, mid), Query(root.R, mid + 1, RR)); return ret; } } public int Update(Tree root, int LL, int RR, int value) { int ret = 0; if (LL == root.ValueL && RR == root.ValueR) { return root.maxscore = value; } else { int mid; mid = (root.ValueL + root.ValueR)/2; if (RR <= mid) ret = Update(root.L, LL, RR, value); else if (LL > mid) ret = Update(root.R, LL, RR, value); else ret = Math.max(Update(root.L, LL, mid, value), Update(root.R, mid + 1, RR, value)); root.maxscore = ret; return ret; } } } // TODO Main Start //System.setIn(new BufferedInputStream(new FileInputStream("c://1754.in"))); int n, m; int a, b; int i; IntervalTree iTree = new IntervalTree(); Tree rootTree; String cmd; Scanner cin = new Scanner(new BufferedInputStream(System.in)); while (cin.hasNext()) { n = cin.nextInt(); m = cin.nextInt(); for(i = 1; i<=n; i++) score[i] = cin.nextInt(); iTree.pos = 0; rootTree = iTree.Build(1, n); for(i = 0; i<m; i++) { cmd = cin.next(); a = cin.nextInt(); b = cin.nextInt(); if (cmd.equals("Q")) { if(a == b) System.out.println(score[a]); else System.out.println(iTree.Query(rootTree, a, b)); } else { score[a] = b; iTree.Update(rootTree, a, a, b); } } } } }

附上C++代码。。。。

#include <cstdio> template <class T> inline T Max(T a, T b) { if (a < b) a = b; return a; } int score[200010]; class Tree { public: Tree *L, *R; int ValueL, ValueR; int maxscore; }; Tree nodes[400010]; class IntervalTree { public: int pos; IntervalTree() { pos = 0; } Tree* NewNode() { return &nodes[pos++]; } Tree* Build(int L, int R) { Tree *rootTree = NewNode(); rootTree->ValueL = L; rootTree->ValueR = R; if (L == R) { rootTree->maxscore = Max(score[L], score[R]); return rootTree; } else { int mid; mid = (L+R)/2; rootTree->L = Build(L, mid); rootTree->R = Build(mid+1, R); rootTree->maxscore = Max(rootTree->L->maxscore, rootTree->R->maxscore); } return rootTree; } int Query(Tree* root, int LL, int RR) { int ret = 0; if (LL == root->ValueL && RR == root->ValueR) { return root->maxscore; } else { int mid; mid = (root->ValueL+root->ValueR)/2; if (RR <= mid) ret = Query(root->L, LL, RR); else if (LL > mid) ret = Query(root->R, LL, RR); else ret = Max(Query(root->L, LL, mid), Query(root->R, mid + 1, RR)); return ret; } } int Update(Tree* root, int LL, int RR, int value) { int ret = 0; if (LL == root->ValueL && RR == root->ValueR) { return root->maxscore = value; } else { int mid; mid = (root->ValueL + root->ValueR)/2; if (RR <= mid) ret = Update(root->L, LL, RR, value); else if (LL > mid) ret = Update(root->R, LL, RR, value); else ret = Max(Update(root->L, LL, mid, value), Update(root->R, mid + 1, RR, value)); root->maxscore = ret; return ret; } } }; int main() { int n, m; int i, j; Tree *rootTree; IntervalTree iTree; char cmd[3]; int a, b; while (scanf("%d%d", &n, &m) != EOF) { for (i = 1; i<=n; i++) scanf("%d", &score[i]); iTree.pos = 0; rootTree = iTree.Build(1, n); for(i = 0; i<m; i++) { scanf("%s%d%d", cmd, &a, &b); if (cmd[0] == 'Q') { if(a == b) printf("%d/n", score[a]); else printf("%d/n", iTree.Query(rootTree, a, b)); } else { score[a] = b; iTree.Update(rootTree, a, a, b); } } } return 0; }