Submission #476902

#	Time	Username	Problem	Language	Result	Execution time	Memory
476902		dooompy	Bridges (APIO19_bridges)	C++17	100 / 100	2379 ms	44144 KiB

bridges

#include "bits/stdc++.h"

using namespace std;

using ll = long long;

const int B = 1000;

int n, m, q;

vector<pair<int, int>> adj[500005];
int u[500005], v[500005], d[500005];
int t[100005], x[100005], y[100005];
bool changed[100005];
vector<int> to_add[B];

stack<int> stck;
int sz[100001], cmp[100001];
int ans[100001];

void reset() {
    iota(cmp + 1, cmp + 1 + n, 1);
    fill(sz + 1, sz + n + 1, 1);
}

int find(int a) {
    while (cmp[a] != a) a = cmp[a];
    return a;
}

void onion(int a, int b) {
    a = find(a), b = find(b);
    if (a == b) return;
    if (sz[a] > sz[b]) swap(a, b);
    stck.push(a);
    sz[b] += sz[a];
    cmp[a] = cmp[b];
}

void rollback(int x) {
    while (stck.size() > x) {
        int k = stck.top();
        stck.pop();
        sz[cmp[k]] -= sz[k];
        cmp[k] = k;
    }
}
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
//    freopen("", "r", stdin);
//    freopen("", "w", stdout);
    cin >> n >> m;

    for (int i = 1; i <= m; i++) {
        cin >> u[i] >> v[i] >> d[i];
    }

    cin >> q;

    for (int i = 1; i <= q; i++) {
        cin >> t[i] >> x[i] >> y[i];
    }

    for (int l = 1; l <= q; l += B) {
        int r = min(q + 1, l + B);
        fill(changed + 1, changed + m + 1, false);
        reset();

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

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

        for (int i = l; i < r; i++) {
            if (t[i] == 1) {
                d[x[i]] = y[i];
            } else {
                to_add[i - l].clear();
                for (auto a : upd) {
                    if (d[x[a]] >= y[i]) to_add[i - l].push_back(x[a]);
                }
            }
        }

        sort(ask.begin(), ask.end(), [&](int a, int b) { return y[a] > y[b]; });
        sort(unchanged.begin(), unchanged.end(), [&](int a, int b) { return d[a] > d[b]; });

        int ptr = 0;
        for (int i : ask) {
            while (ptr < unchanged.size() && d[unchanged[ptr]] >= y[i]) {
                onion(v[unchanged[ptr]], u[unchanged[ptr]]);
                ptr++;
            }
            int now = stck.size();

            for (auto a : to_add[i - l]) {
                onion(v[a], u[a]);
            }

            ans[i] = sz[find(x[i])];
            rollback(now);
        }
    }

    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:41:24: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   41 |     while (stck.size() > x) {
      |            ~~~~~~~~~~~~^~~
bridges.cpp: In function 'int main()':
bridges.cpp:100:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |             while (ptr < unchanged.size() && d[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