Submission #766152

#	Time	Username	Problem	Language	Result	Execution time	Memory
766152		marvinthang	Simurgh (IOI17_simurgh)	C++17	100 / 100	122 ms	17220 KiB

simurgh

/*************************************
*    author: marvinthang             *
*    created: 25.06.2023 11:26:35    *
*************************************/

#include "simurgh.h"
#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i--; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
    #include "debug.h"
#else
    #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
    #define DB(...) 23
    #define db(...) 23
    #define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

struct DisjointSet {
    
    int n, *lab = nullptr;

    DisjointSet(int _n = 0) {
        resize(_n);
    }

    void reset(void) {
        memset(lab, -1, (n + 1) * sizeof(int));
    }

    void resize(int _n) {
         if (lab != nullptr) delete[] lab;
         n = _n;
         lab = new int[n + 1];
         reset();
    }

    int find(int u) {
        assert(u <= n);
        return lab[u] < 0 ? u : lab[u] = find(lab[u]);
    }

    bool connected(int u, int v) { return find(u) == find(v); }
    bool isRoot(int u) { return lab[u] < 0; }
    int size(int u) { return -lab[find(u)]; }

    bool join(int u, int v) {
        if ((u = find(u)) == (v = find(v))) return false;
        if (lab[u] > lab[v]) swap(u, v);
        lab[u] += lab[v];
        lab[v] = u;
        return true;
    }

};

using DSU = DisjointSet;

// end of template

const int MAX = 505;

int timeDfs;
vector <int> tree, r_edge, states;
vector <bool> used;
vector <vector <int>> adj;
vector <int> U, V, low, num, par, low_id, pos;

void dfs(int u) {
	num[u] = ++timeDfs;
	for (int id: adj[u]) if (!used[id]) {
		used[id] = true;
		if (u == V[id]) swap(U[id], V[id]);
		int v = V[id];
		if (!num[v]) {
			tree.push_back(id);
			par[v] = id;
			dfs(v);
			if (minimize(low[u], low[v])) low_id[u] = low_id[v];
			if (low[v] > num[u]) states[id] = 1;
		} else {
			assert(num[u] > num[v]);
			r_edge.push_back(id);
			if (minimize(low[u], num[v])) low_id[u] = id;
		}
	}
}

vector <int> trace_path(int u, int p) {
	vector <int> res;
	while (u != p) {
		res.push_back(par[u]);
		u = U[par[u]];
	}
	return res;
}

vector <int> find_roads(int n, vector <int> u, vector <int> v) {
	int m = u.size();
	adj.assign(n, vector<int>());
	tree.clear();
	r_edge.clear();
	U = u; V = v;
	timeDfs = 0;

	num.assign(n, 0);
	low.assign(n, MAX);
	par.assign(n, 0);
	low_id.assign(n, 0);

	pos.assign(m, -1);
	used.assign(m, false);
	states.assign(m, -1);

	REP(i, m) {
		adj[u[i]].push_back(i);
		adj[v[i]].push_back(i);
	}
	dfs(0);

	REP(i, n - 1) pos[tree[i]] = i;
	int cur = count_common_roads(tree);

	for (int e1: tree) if (!~states[e1]) {
		int e2 = low_id[V[e1]];
		vector <int> p = trace_path(U[e2], V[e2]);
		REP(i, p.size()) if (p[i] == e1) {
			swap(p[i], p[0]);
			break;
		}
		bool done = false;
		REP(i, p.size()) {
			int e = p[i];
			tree[pos[e]] = e2;
			int nxt = count_common_roads(tree);
			tree[pos[e]] = e;
			if (nxt != cur) {
				states[e2] = nxt > cur;
				states[e] = nxt < cur;
				REP(j, i) states[p[j]] = states[e2];
				done = true;
				break;
			} else if (~states[e]) {
				states[e2] = states[e];
				REP(j, i + 1) states[p[j]] = states[e];
				done = true;
				break;
			}
		}
		if (!done) for (int e: p) states[e] = 0;
	}
	REP(u, n) {
		vector <int> f;
		for (int id: adj[u]) if (!~states[id]) f.push_back(id);
		while (true) {
			auto ask = [&] (int p) {
				if (!p) return 0;
				vector <int> a(f.begin(), f.begin() + p);
				DSU dsu(n);
				for (int x: a) dsu.join(U[x], V[x]);
				int cnt = 0;
				for (int x: tree) if (dsu.join(U[x], V[x])) {
					cnt += states[x];
					a.push_back(x);
				}
				return count_common_roads(a) - cnt;
			};
			int x = ask(f.size());
			if (!x) break;
			int l = 0, r = (int) f.size() - 1;
			while (l <= r) {
				int m = l + r >> 1;
				if (ask(m + 1) == x) r = m - 1;
				else l = m + 1;
			}
			while (f.size() > l) {
				states[f.back()] = (int) f.size() == l + 1;
				f.pop_back();
			}
		}
	}
	vector <int> res;
	REP(i, m) if (states[i] == 1) res.push_back(i);	
	return res;
}

#ifdef LOCAL
#include "simurgh.h"

#include <cstdio>
#include <cassert>
#include <vector>
#include <cstdlib>
#include <string>

using namespace std;

static int MAXQ = 30000;

static int n, m, q = 0;
static vector<int> u, v;
static vector<bool> goal;

static void wrong_answer() {
	printf("NO\n");
	exit(0);
}

static bool is_valid(const vector<int>& r) {
	if(int(r.size()) != n - 1)
		return false;

	for(int i = 0; i < n - 1; i++)
		if (r[i] < 0 || r[i] >= m)
			return false;

	return true;
}

static int _count_common_roads_internal(const vector<int>& r) {
	if(!is_valid(r))
		wrong_answer();

	int common = 0;
	for(int i = 0; i < n - 1; i++) {
		bool is_common = goal[r[i]];
		if (is_common)
			common++;
	}

	return common;	
}

int count_common_roads(const vector<int>& r) {
	q++;
	if(q > MAXQ)
		wrong_answer();

	return _count_common_roads_internal(r);
}

int main() {
	file("simurgh");
	assert(2 == scanf("%d %d", &n, &m));

	u.resize(m);
	v.resize(m);

	for(int i = 0; i < m; i++)
		assert(2 == scanf("%d %d", &u[i], &v[i]));

	goal.resize(m, false);

	for(int i = 0; i < n - 1; i++) {
		int id;
		assert(1 == scanf("%d", &id));
		goal[id] = true;
	}

	vector<int> res = find_roads(n, u, v);

	if(_count_common_roads_internal(res) != n - 1)
		wrong_answer();
	printf("YES\n");
	printf("q = %d\n", q);

	return 0;
}
#endif

Compilation message (stderr)

simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:199:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  199 |     int m = l + r >> 1;
      |             ~~^~~
simurgh.cpp:203:20: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  203 |    while (f.size() > l) {
      |           ~~~~~~~~~^~~

• Subtask 1: 13 / 13
• Subtask 2: 17 / 17
• Subtask 3: 21 / 21
• Subtask 4: 19 / 19
• Subtask 5: 30 / 30