Submission #1210632

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210632		dubabuba	Bridges (APIO19_bridges)	C++17	100 / 100	2245 ms	6048 KiB

bridges

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

typedef pair<int, int> pii;
#define ff first
#define ss second
#define MP make_pair

const int mxn = 1e5 + 10;
const int BLOCK_sz = 550;
int n, m, q, weight[mxn];
vector<pii> edges(mxn);
vector<pii> query(mxn);
bool changed[mxn];
int type[mxn];
int ans[mxn];

namespace DSU {
	int par[mxn];
	stack<pair<pii, pii>> hist;

	int parent(int u) { return par[u] < 0 ? u : parent(par[u]); }
	void unite(int u, int v) {
		u = parent(u);
		v = parent(v);
		if(u == v) return;

		if(par[u] > par[v]) swap(u, v);
		hist.push(MP(MP(u, par[u]), MP(v, par[v])));
		par[u] += par[v];
		par[v] = u;
	}
	void roll_back(int sz) {
		while(hist.size() > sz) {
			int u, pu, v, pv;
			tie(u, pu) = hist.top().ff;
			tie(v, pv) = hist.top().ss;

			par[u] = pu;
			par[v] = pv;
			hist.pop();
		}
	}

	void clear(int n) {
		memset(par, -1, sizeof(int) * (n + 5));
		while(hist.size()) hist.pop();
	}
};

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	cin >> n >> m;
	for(int i = 1; i <= m; i++) {
		cin >> edges[i].ff >> edges[i].ss >> weight[i];
	}

	cin >> q;
	for(int i = 0; i < q; i++) {
		cin >> type[i] >> query[i].ff >> query[i].ss;
	}

	function<void(int)> connect = [&](int i) { DSU::unite(edges[i].ff, edges[i].ss); }; // i - edge ID
	// for(int i = 1; i <= m; i++)
	// 	cout << i << ": " << edges[i].ff << " " << edges[i].ss << " = " << weight[i] << endl;
	for(int L = 0; L < q; L += BLOCK_sz) {
		int R = min(L + BLOCK_sz, q);
		for(int i = 1; i <= m; i++)
			changed[i] = 0;

		vector<int> ask, upt;
		for(int i = L; i < R; i++) {
			int x = query[i].ff; // edge ID or node
			int w = query[i].ss;
			if(type[i] == 1) {
				changed[x] = 1;
				upt.push_back(x);
			}
			else {
				ask.push_back(i);
			}
		}

		vector<int> UC;
		for(int i = 1; i <= m; i++) {
			if(!changed[i])
				UC.push_back(i);
		}

		sort(ask.begin(), ask.end(), [&](int i, int j) { return query[i].ss > query[j].ss; }); // i, j - query ID
		sort(UC.begin(), UC.end(), [&](int i, int j) { return weight[i] > weight[j]; }); // i, j - edge ID

		vector<int> join[BLOCK_sz];
		for(int i = L; i < R; i++) {
			int x = query[i].ff;
			int w = query[i].ss;
			if(type[i] == 1) {
				weight[x] = w;
				// cout << "update " << x << " := " << w << endl;
			}
			else {
				// cout << "\nquery = " << i << endl;
				for(int j : upt) {
					// cout << "weight " << j << " = " << weight[j] << endl;
					if(weight[j] >= w)
						join[i - L].push_back(j);
				}
			}
		}

		DSU::clear(n);
		int ptr = 0;
		for(int cur : ask) { // cur - current query ID
			const int u = query[cur].ff;
			const int w = query[cur].ss;

			while(ptr < UC.size()) {
				int e = UC[ptr];
				if(weight[e] < w) break;
				connect(e);
				ptr++;
			}

			const int snap = DSU::hist.size();
			for(int i : join[cur - L])
				connect(i);

			int p = DSU::parent(u);
			ans[cur] = -DSU::par[p];
			DSU::roll_back(snap); // sus
		}

		// for(int i = L; i < R; i++) {
		// 	if(type[i] == 2) continue;
		// 	int e = query[i].ff;
		// 	int w = query[i].ss;
		// 	weight[e] = w; // sus
		// }
	}

	for(int i = 0; i < q; i++) {
		if(type[i] == 2) {
			cout << ans[i] << endl;
		}
	}

	return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 14 / 14
• Subtask 5: 13 / 13
• Subtask 6: 27 / 27