Submission #939694

#	Time	Username	Problem	Language	Result	Execution time	Memory
939694		HiepVu217	Bridges (APIO19_bridges)	C++17	100 / 100	1782 ms	34704 KiB

bridges

#include <bits/stdc++.h>
#define FOR(i, x, y) for (int i = x; i < y; i++)
using namespace std;
const int N = 1e5 + 17, M = 1e3;
int n, m, q;
int u[N], v[N], w[N], t[N], x[N], y[N];
int par[N], sz[N], ans[N];
bool change[N];
vector <int> ed[N];
stack <int> rb;
int root (int u)
{
    while (u != par[u])
    {
        u = par[u];
    }
    return u;
}
void join (int u, int v)
{
    int ru = root(u), rv = root(v);
    if (ru == rv)
    {
        return;
    }
    if (sz[ru] < sz[rv])
    {
        swap (ru, rv);
    }
    rb.push(rv);
    par[rv] =   ru;
    sz[ru] += sz[rv];
}
void rollback (int x)
{
	while (rb.size() > x)
    {
		int s = rb.top();
		rb.pop();
		sz[par[s]] -= sz[s];
		par[s] = s;
	}
}
bool cmp1 (int a, int b)
{
    return w[a] > w[b];
}
bool cmp2 (int a, int b)
{
    return y[a] > y[b];
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= m; ++i)
    {
        cin >> u[i] >> v[i] >> w[i];
    }
    cin >> q;
    for (int i = 1; i <= q; ++i)
    {
        cin >> t[i] >> x[i] >> y[i];
    }
    for (int l = 1; l <= q; l += M) {
		int r = min(q + 1, l + M);
		iota (par + 1, par + n + 1, 1);
        fill (sz + 1, sz + n + 1, 1);
		fill(change + 1, change + m + 1, false);

		vector<int> ask, upd, unchanged;
		FOR(i, l, r) {
			if (t[i] == 1) {
				change[x[i]] = true;
				upd.push_back(i);
			} else ask.push_back(i);
		}
		FOR(i, 1, m + 1) if (!change[i]) unchanged.push_back(i);

		FOR(i, l, r) {
			if (t[i] == 1) w[x[i]] = y[i];
			else {
				ed[i - l].clear();
				for (int j : upd)
					if (w[x[j]] >= y[i]) ed[i - l].push_back(x[j]);
			}
		}

		sort(ask.begin(), ask.end(), cmp2);
		sort(unchanged.begin(), unchanged.end(), cmp1);

		int ptr = 0;
		for (int i : ask) {
			while (ptr < unchanged.size() && w[unchanged[ptr]] >= y[i]) {
				join(u[unchanged[ptr]], v[unchanged[ptr]]);
				ptr++;
			}
			int prev_size = rb.size();
			for (int j : ed[i - l]) join(u[j], v[j]);
			ans[i] = sz[root(x[i])];
			rollback(prev_size);
		}
	}
    for (int i = 1; i <= q; ++i)
    {
        if (t[i] == 2)
        {
            cout << ans[i] << "\n";
        }
    }
}

Compilation message (stderr)

bridges.cpp: In function 'void rollback(int)':
bridges.cpp:36:19: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   36 |  while (rb.size() > x)
      |         ~~~~~~~~~~^~~
bridges.cpp: In function 'int main()':
bridges.cpp:96:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |    while (ptr < unchanged.size() && w[unchanged[ptr]] >= y[i]) {
      |           ~~~~^~~~~~~~~~~~~~~~~~

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