Submission #407543

#	Time	Username	Problem	Language	Result	Execution time	Memory
407543		Kevin_Zhang_TW	Simurgh (IOI17_simurgh)	C++17	0 / 100	2423 ms	1048580 KiB

simurgh

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

const int MAX_N = 505;

#include "simurgh.h"

map< pair<int,int>, int > id;

int qry(const vector<int> &r) { return count_common_roads(r); }

int pa[MAX_N], dep[MAX_N];

vector<int> edge[MAX_N];

struct dsu {
	vector<int> g, sz;
	dsu (int n) { g.resize(n+10), sz.resize(n+10, 1), iota(AI(g), 0); }
	int F(int i) { return i == g[i] ? i : g[i] = F(g[i]); }
	int S(int i) { return sz[ F(i) ]; }
	bool M(int a, int b) { 
		a = F(a), b = F(b);
		if (a == b) return false;
		return sz[a] += sz[b], g[b] = a, true;
	}
};

void dfs(int x, int lst) {
	pa[x] = lst;
	for (int u : edge[x]) if (u != lst) {
		dep[u] = dep[x] + 1;
	}
}

std::vector<int> find_roads(int n, std::vector<int> u, std::vector<int> v) {
	static int cnt;
	assert(++cnt == 1);
	int m = u.size();


	vector<int> old, on_tree(m);
	{
		dsu D(n); 

		for (int i = 0;i < m;++i) {
			id[ {u[i], v[i]} ] = i;
			id[ {v[i], u[i]} ] = i;
			if (D.M(v[i], u[i])) {
				edge[ u[i] ].pb( v[i] );
				edge[ v[i] ].pb( u[i] );
				old.pb(i);
				on_tree[i] = true;
			}
		}
	}
	dfs(0, 0);

	int old_val = qry(old);

	dsu D(m + 2);
	int Z = m, O = m+1;

	auto sure = [&](int a) { 
		return D.F(a) == D.F(Z) || D.F(a) == D.F(O);
	};

	for (int i = 0;i < m;++i) {
		if (on_tree[i]) continue;

		int a = u[i], b = v[i];
		vector<int> all;
		while (a != b) {
			if (dep[a] < dep[b]) swap(a, b);
			all.pb( id[ {a, pa[a]} ] );
			a = pa[a];
		}

		for (int j : all) {
			if (sure(i) && sure(j)) continue;
			if (D.F(i) == D.F(j)) continue;
			vector<int> now = old;
			now.erase(find(AI(now), j));
			now.pb(i);

			int nv = qry(now);

			if (nv == old_val) D.M(i, j);
			if (nv > old_val) D.M(i, O), D.M(j, Z);
			if (nv < old_val) D.M(i, Z), D.M(j, O);

		}

	}

	for (int i = 0;i < m;++i) if (D.S(i) == 1)
		D.M(i, O);

	vector<int> res;
	for (int i = 0;i < m;++i) {
		if (D.F(i) == D.F(O))
			res.pb(i);
	}

	return res;

	
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30