Submission #929166

#	Time	Username	Problem	Language	Result	Execution time	Memory
929166		Joshua_Andersson	Joker (BOI20_joker)	C++14	0 / 100	2052 ms	21060 KiB

Joker

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define int ll
const int inf = int(1e18);

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> p2;

#define rep(i, high) for (int i = 0; i < high; i++)
#define repp(i, low, high) for (int i = low; i < high; i++)
#define repe(i, container) for (auto& i : container)
#define sz(container) ((int)container.size())

inline void fast() { ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); }

struct change
{
	int a, b;
	int oldpar, oldxor, oldsize;
};

struct UF
{
	vector<change> updates;
	vi size;
	vi par;
	vi parity;

	UF(int n) : size(n, 1), parity(n), par(n)
	{
		rep(i, n)par[i] = i;
	}

	int find(int x) { return x == par[x] ? x : find(par[x]); }
	int getparity(int x) { return x == par[x] ? parity[x] : parity[x] ^ getparity(par[x]); }
	bool oddcycle(int a, int b)
	{
		return getparity(a) == getparity(b);
	}

	void merge(int a, int b)
	{
		if (size[find(a)] < size[find(b)]) swap(a, b);
		int childa = a;
		int childb = b;
		a = find(a); b = find(b);
		change c({a,b,par[b],parity[b],size[a]});
		updates.push_back(c);

		if (a != b)
		{
			parity[b] = getparity(childb) ^ getparity(childa) ^ 1;
			size[a] += size[b];
			par[b] = a;
		}
	}

	void rollback()
	{
		change c = updates.back();
		updates.pop_back();
		par[c.b] = c.oldpar;
		parity[c.b] = c.oldxor;
		size[c.a] = c.oldsize;
	}
};

signed main()
{
	fast();

	int n, m, q;
	cin >> n >> m >> q;
	vector<p2> edgelist;
	rep(i, m)
	{
		int a, b;
		cin >> a >> b;
		a--; b--;
		edgelist.emplace_back(a, b);
	}
	//shuffle(edgelist.begin(), prev(edgelist.end()), mt19937(3436876));

	UF uf(n);
	vi right(m, inf);
	bool anyodd = 0;
	auto add = [&](int i)
	{
		int a, b;
		tie(a, b) = edgelist[i];
		int ret = 0;
		if (uf.find(a) == uf.find(b)) ret = uf.oddcycle(a, b);
		uf.merge(a, b);
		return ret;
	};
	rep(i, m)
	{
		int lo = i;
		int hi = m;
		while (lo+1<hi)
		{
			int mid = (lo + hi) / 2;
			bool odd = 0;
			for (int j = m - 1; j >= mid; j--) odd |= add(j);
			for (int j = m - 1; j >= mid; j--) uf.rollback();
			if (odd) lo = mid;
			else hi = mid;
		}
		right[i] = lo;

		if (anyodd) right[i] = -1;
		anyodd |= add(i);
	}

	//vvi queries(m);
	while (q--)
	{
		int l, r;
		cin >> l >> r;
		l--; r--;
		
		cout << (r+1<=right[l] ? "YES" : "NO") << "\n";
	}

	return 0;
}

Compilation message (stderr)

Joker.cpp: In constructor 'UF::UF(ll)':
Joker.cpp:30:5: warning: 'UF::parity' will be initialized after [-Wreorder]
   30 |  vi parity;
      |     ^~~~~~
Joker.cpp:29:5: warning:   'vi UF::par' [-Wreorder]
   29 |  vi par;
      |     ^~~
Joker.cpp:32:2: warning:   when initialized here [-Wreorder]
   32 |  UF(int n) : size(n, 1), parity(n), par(n)
      |  ^~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29