Submission #2236026

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Source Code Expand

#include <iostream>
#include <fstream>
#include <string> 
#include <cmath>  
#include <cstdlib>
#include <ctime>
#include <vector>
#include <list>  
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <functional>

using namespace std;
using ll = long long;
using ull = unsigned long long;

#define FOR(i, m, n) for(int i = int(m);i < int(n);i++)
#define REFOR(i, m, n) for(int i = int(n - 1);i >= int(m);i--)
#define REP(i,n) for(int i = 0; i < int(n); i++)
#define REREP(i,n) for(int i = int(n - 1); i >= 0; i--)
#define VI vector<int>
#define VVI vector<vector<int>>
#define VVVI vector<vector<vector<int>>>
#define VL vector<ll>
#define VVL vector<vector<ll>>
#define VB vector<bool>
#define VVB vector<vector<bool>>
#define PAIR pair<int,int>
#define MP make_pair
#define VP vector<pair<int,int>>
#define VS vector<string>
#define MAP map<int,int>
#define QUE queue<int>
#define DEQ deque<int>
#define PQUE priority_queue<int> //5,5,4,3,3,2,...
#define REPQUE priority_queue<int, vector<int>, greater<int>> //1,1,2,3,4,4,5,...
#define SUM(obj) accumulate((obj).begin(), (obj).end(), 0)
#define SORT(obj) sort((obj).begin(), (obj).end()) // 1,2,3,4,5...
#define RESORT(obj) sort((obj).begin(), (obj).end(), greater<int>()) // 5,4,3,2,1...
#define UB(obj,n) upper_bound((obj).begin(), (obj).end(), n) //itr > n
#define LB(obj,n) lower_bound((obj).begin(), (obj).end(), n) //itr>= n

const ll MOD = (ll)1e9 + 7;
const ll INF = (ll)1e17;

int gcd(int a, int b) {
	if (a == 0 || b == 0) return 0;
	if (a < b) swap(a, b);
	while (b != 0) {
		a = a%b;
		swap(a, b);
	}
	return a;
}

int lcm(int a, int b) {
	if (a == 0 || b == 0) return 0;
	return a / gcd(a, b)*b;
}

vector<bool> Eratosthenes(int N) {
	vector<bool> Eratosthenes(N + 1, true);
	Eratosthenes[0] = false;
	if (N == 0) return Eratosthenes;
	Eratosthenes[1] = false;
	for (int i = 1; i*i <= N; i++) if (Eratosthenes[i]) for (int j = 2 * i; j <= N; j += i) Eratosthenes[j] = false;
	return Eratosthenes;
}

bool pcheck(int N) {
	if (N == 0 || N == 1) return false;
	for (int i = 2; i*i <= N; i++) if (N % i == 0) return false;
	return true;
}

////combination mod-------------------------------------------------------------------------
//
//vector<ll> f;//erase this line when you use!
//
////vector including modulus of N!
//vector<ll> factorial(ll N, ll quotient) {
//	vector<ll> factorial(N + 1, 1);
//	for (ll i = 1; i <= N; i++) {
//		factorial[i] *=factorial[i - 1]*i;
//		factorial[i] %= quotient;
//	}
//	return factorial;
//}
//
////repeat square method y = x^n mod quotient 
//ll rsm(ll x,ll n,ll quotient){
//	ll y = 1;
//	while (n > 0) {
//		if ((n & 1) == 1) {
//			y *= x;
//			y %= quotient;
//		}
//		x *= x;
//		x %= quotient;
//		n >>= 1; 
//	}
//	return y;
//}
//
////modulus of nCk - combination mod 
//ll nCk(ll n, ll k, ll quotient) {
//	
//	ll nCk = (f[n] % quotient);
//	nCk *= rsm(f[k], quotient - 2, quotient);
//	nCk %= quotient;
//	nCk *= rsm(f[n - k], quotient - 2, quotient);
//	return (nCk % quotient);
//}
////------------------------------------------------------------

////union-find---------------------------------------------------
//int node[10];
//
//int root(int n) {
//	if (node[n] == n) return n;
//	else return node[n] = root(node[n]);
//}
//
//void unite(int n, int m) {
//	if (n > m) swap(n, m);
//	n = root(n);
//	m = root(m);
//	if (n == m) return;
//	else node[m] = n;
//}
//-------------------------------------------------------------

//void dijkstra(int start) {
//	priority_queue<PAIR, vector<PAIR>, greater<PAIR>> pq;
//	dist[start][start] = 0;
//	pq.push({ 0,start });
//	while (!pq.empty()) {
//		int from = pq.top().second;
//		pq.pop();
//		REP(i, edge[from].size()) {
//			int to = edge[from][i].first;
//			if (dist[start][to] > dist[start][from] + edge[from][i].second) {
//				dist[start][to] = dist[start][from] + edge[from][i].second;
//				pq.push({ dist[start][from] + edge[from][i].second,to });
//			}
//		}
//	}
//}


void ANS(bool flag) {
	cout << ((flag) ? "YES" : "NO") << endl;
}

void Ans(bool flag) {
	cout << ((flag) ? "Yes" : "No") << endl;
}

void ans(bool flag) {
	cout << ((flag) ? "yes" : "no") << endl;
}

class lca {
public:
	int node;
	int MAXLOG2;
	VVI edge;
	VI depth;
	VVI parent;

	void set(int node_,int MAXLOG2_){
		node = node_;
		MAXLOG2 = MAXLOG2_;
		edge.resize(node);
		depth.resize(node);
		parent.resize(node);
		REP(i, node) parent[i].resize(MAXLOG2);
	}

	void dfs(int root, int root_from) {
		depth[root] = 0;
		parent[root][0] = root_from;
		stack<pair<int, int>> st;
		st.push({ root,root_from });

		while (!st.empty()) {
			int from = st.top().first;
			int from_from = st.top().second;
			st.pop();
			REP(i, edge[from].size()) {
				int to = edge[from][i];
				if (to != from_from) {
					depth[to] = depth[from] + 1;
					parent[to][0] = from;
					st.push({ to,from });
				}
			}
		}
		return;
	}

	void initialize(int N) {
		REP(k, MAXLOG2 - 1) {
			REP(i, N) {
				if (parent[i][k] < 0) parent[i][k + 1] = -1;
				else parent[i][k + 1] = parent[parent[i][k]][k];
			}
		}
		return;
	}

	//get least common ancestor
	int get(int a, int b) {
		if (depth[a] > depth[b]) swap(a, b);
		REP(k, MAXLOG2 - 1) if (((depth[b] - depth[a]) >> k) & 1) b = parent[b][k];
		if (a == b) return a;
		REREP(k, MAXLOG2) {
			if (parent[a][k] != parent[b][k]) {
				a = parent[a][k];
				b = parent[b][k];
			}
		}
		return parent[a][0];
	}
};

int main() {
	int N;
	cin >> N;
	lca T;
	T.set(N, 20);
	REP(i, N - 1) {
		int x, y;
		cin >> x >> y;
		x--; y--;
		T.edge[x].push_back(y);
		T.edge[y].push_back(x);
	}
	T.dfs(0, -1);
	T.initialize(N);
	int Q;
	cin >> Q;
	VI a(Q), b(Q);
	REP(i,Q) cin >> a[i] >> b[i];
	
	REP(i,Q){
		a[i]--; b[i]--;
		int c = T.get(a[i], b[i]);
		cout << T.depth[a[i]] + T.depth[b[i]] - 2 * T.depth[c] + 1 << endl;
	}
	return 0;
}

Submission Info

Judge Result