CompetitiveProgramming

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:heavy_check_mark: kyopro/test/LCA_yosupo-judge.test.cpp

Depends on

Code

#define PROBLEM "https://judge.yosupo.jp/problem/lca"

#include "../library/template/template.cpp"
#include "../library/graph/graph_template.cpp"

#include "../library/datastructure/sparsetable.cpp"

#include "../library/graph/LCA.cpp"

int main() {

	int n, q;
	scanf("%d%d", &n, &q);
	graph<int> tree(n, true, false);
	int p;
	rep(i, n - 1) {
		scanf("%d", &p);
		tree.add_edge(p, i + 1);
	}
	LCA lca(tree, n, 0);
	int v;
	rep(i, q) {
		scanf("%d%d", &p, &v);
		printf("%d\n", lca.query(p, v));
	}

	Please AC;
}
#line 1 "kyopro/test/LCA_yosupo-judge.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/lca"

#line 1 "kyopro/library/template/template.cpp"
/*
* @title template
* @docs kyopro/docs/template.md
*/


/*
このコード、と～おれ!
Be accepted!
∧＿∧　
（｡･ω･｡)つ━☆・*。
⊂　　 ノ 　　　・゜+.
　しーＪ　　　°。+ *´¨)
 　　　　　　　　　.· ´¸.·*´¨) ¸.·*¨)
		  　　　　　　　　　　(¸.·´ (¸.·'* ☆
*/

#include <cstdio>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstring>
#include <vector>
#include <numeric>
#include <iostream>
#include <random>
#include <map>
#include <unordered_map>
#include <queue>
#include <regex>
#include <functional>
#include <complex>
#include <list>
#include <cassert>
#include <iomanip>
#include <set>
#include <stack>
#include <bitset>
#include <array>
#include <chrono>

//#pragma GCC target("arch=skylake-avx512")
//#pragma GCC target ("avx2")
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define repeat(i, n, m) for(int i = n; i < (m); ++i)
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define printynl(a) printf(a ? "yes\n" : "no\n")
#define printyn(a) printf(a ? "Yes\n" : "No\n")
#define printYN(a) printf(a ? "YES\n" : "NO\n")
#define printim(a) printf(a ? "possible\n" : "imposible\n")
#define printdb(a) printf("%.50lf\n", a)
#define printLdb(a) printf("%.50Lf\n", a)
#define printdbd(a) printf("%.16lf\n", a)
#define prints(s) printf("%s\n", s.c_str())
#define all(x) (x).begin(), (x).end()
#define deg_to_rad(deg) (((deg)/360.0L)*2.0L*PI)
#define rad_to_deg(rad) (((rad)/2.0L/PI)*360.0L)
#define Please return
#define AC 0
#define manhattan_dist(a, b, c, d) (abs(a - c) + abs(b - d))

using ll = long long;
using ull = unsigned long long;

constexpr int INF = 1073741823;
constexpr int MINF = -1073741823;
constexpr ll LINF = ll(4661686018427387903);
constexpr ll MOD = 1e9 + 7;
constexpr ll mod = 998244353;
constexpr long double eps = 1e-6;
const long double PI = acosl(-1.0L);

using namespace std;

void scans(string& str) {
	char c;
	str = "";
	scanf("%c", &c);
	if (c == '\n')scanf("%c", &c);
	while (c != '\n' && c != -1 && c != ' ') {
		str += c;
		scanf("%c", &c);
	}
}

void scanc(char& str) {
	char c;
	scanf("%c", &c);
	if (c == -1)return;
	while (c == '\n') {
		scanf("%c", &c);
	}
	str = c;
}

double acot(double x) {
	return PI / 2 - atan(x);
}

ll LSB(ll n) { return (n & (-n)); }

template<typename T>
inline T chmin(T& a, const T& b) {
	if (a > b)a = b;
	return a;
}

template<typename T>
inline T chmax(T& a, const T& b) {
	if (a < b)a = b;
	return a;
}

////cpp_int
//#include <boost/multiprecision/cpp_int.hpp>
//#include <boost/multiprecision/cpp_dec_float.hpp>
//using namespace boost::multiprecision;

//atcoder library
//#include <atcoder/all>
//using namespace atcoder;

//random_device seed_gen;
//mt19937 engine(seed_gen());
//uniform_distribution dist(-1.0, 1.0);

/*----------------------------------------------------------------------------------*/
#line 1 "kyopro/library/graph/graph_template.cpp"
/*
* @title template(graph)
* @docs kyopro/docs/graph_template.md
*/

template<typename T>
struct edge {
	T cost;
	int from, to;

	edge(int from, int to) : from(from), to(to), cost(T(1)) {}
	edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
};

template<typename T = int>
struct graph {

	int n;
	bool directed, weighted;

	vector<vector<edge<T>>> g;

	graph(int n, bool directed, bool weighted) : g(n), n(n), directed(directed), weighted(weighted) {}

	void add_edge(int from, int to, T cost = T(1)) {
		g[from].emplace_back(from, to, cost);
		if (not directed) {
			g[to].emplace_back(to, from, cost);
		}
	}

	vector<edge<T>>& operator[](const int& idx) {
		return g[idx];
	}

	void read(int e, bool one_indexed) {
		int a, b, c = 1;
		while (e--) {
			scanf("%d%d", &a, &b);
			if (weighted) {
				scanf("%d", &c);
			}
			if (one_indexed)--a, --b;
			add_edge(a, b, c);
		}
	}

	void read(int e, bool one_indexed, const string& format) {
		int a, b;
		T c = T(1);
		while (e--) {
			scanf("%d%d", &a, &b);
			if (weighted) {
				scanf(format.c_str(), &c);
			}
			if (one_indexed)--a, --b;
			add_edge(a, b, c);
		}
	}

};
#line 5 "kyopro/test/LCA_yosupo-judge.test.cpp"

#line 1 "kyopro/library/datastructure/sparsetable.cpp"
/*
* @title sparse-table
* @docs kyopro/docs/sparsetable.md
*/

//RMQ <O(n log n), O(1)>
template<typename T>
struct sparsetable {

	vector<vector<T>> table;
	vector<int> logtable;
	vector<int> a;
	int n;

	// 渡す配列, サイズ
	sparsetable(const vector<T> a, int siz) : n(siz), a(a) {
		logtable.assign(n + 1, 0);
		for (int i = 2; i <= n; ++i)logtable[i] = logtable[i >> 1] + 1;
		table.assign(n, vector<T>(logtable[n] + 1, 0));
	}

	//リストバージョン
	sparsetable(initializer_list<T> init) {
		a = init[0];
		n = init[1];
		logtable.assign(n + 1, 0);
		for (int i = 2; i <= n; ++i)logtable[i] = logtable[i >> 1] + 1;
		table.assign(n, vector<T>(logtable[n] + 1, 0));
	}

	//配列と大きさを渡して初期化
	void init(const vector<T> aa, int siz) {
		a = aa;
		n = siz;
		logtable.assign(n + 1, 0);
		for (int i = 2; i <= n; ++i)logtable[i] = logtable[i >> 1] + 1;
		table.assign(n, vector<T>(logtable[n] + 1, 0));
	}

	//構築 O(n log n)
	void build() {
		for (int k = 0; (1 << k) <= n; ++k) {
			for (int i = 0; i + (1 << k) <= n; ++i) {
				if (k) table[i][k] = (a[table[i][k - 1]] < a[table[i + (1 << (k - 1))][k - 1]] ? table[i][k - 1] : table[i + (1 << (k - 1))][k - 1]);
				else table[i][k] = i;
			}
		}
	}

	//[l, r) の RMQ O(1)
	int query(int l, int r) {
		int k = logtable[r - l];
		return (a[table[l][k]] < a[table[r - (1 << k)][k]] ? table[l][k] : table[r - (1 << k)][k]);
	}

};

#line 7 "kyopro/test/LCA_yosupo-judge.test.cpp"

#line 1 "kyopro/library/graph/LCA.cpp"
/*
* @title lowest-common-ancestor
* @docs kyopro/docs/LCA.md
*/


template<typename T>
void eulertour(const int& now, const int& bef, int& cnt, graph<T>& graph, const int& d, vector<int>& vs, vector<int>& depth, vector<int>& id) {
	depth.emplace_back(d);
	vs.emplace_back(now);
	id[now] = min(id[now], cnt);
	for (const auto& aa : graph[now]) {
		if (aa.to != bef) {
			++cnt;
			eulertour(aa.to, now, cnt, graph, d + 1, vs, depth, id);
			++cnt;
			depth.emplace_back(d);
			vs.emplace_back(now);
		}
	}
}

template<typename T = int>
struct LCA {

	vector<int> vs, depth, id, tmp = { 0 };
	graph<T> tree;
	sparsetable<int> table{ tmp, 0 };
	int n, root;

	//木,　大きさ, 根
	LCA(graph<T> tree, int n, int root) : tree(tree), n(n), root(root) {
		id.assign(n, INF);
		int cnt = 0, d = 0;
		eulertour(root, -1, cnt, tree, d, vs, depth, id);
		table.init(depth, depth.size());
		table.build();
	}

	//LCA である頂点を返す
	int query(int l, int r) {
		if (id[l] > id[r])swap(l, r);
		return vs[table.query(id[l], id[r] + 1)];
	}

	int depthq(int n) {
		return depth[id[n]];
	}
};

#line 9 "kyopro/test/LCA_yosupo-judge.test.cpp"

int main() {

	int n, q;
	scanf("%d%d", &n, &q);
	graph<int> tree(n, true, false);
	int p;
	rep(i, n - 1) {
		scanf("%d", &p);
		tree.add_edge(p, i + 1);
	}
	LCA lca(tree, n, 0);
	int v;
	rep(i, q) {
		scanf("%d%d", &p, &v);
		printf("%d\n", lca.query(p, v));
	}

	Please AC;
}
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