Submission #1266149

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266149		icebear	Bridges (APIO19_bridges)	C++20	100 / 100	1298 ms	7860 KiB

bridges

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

typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;

template<class T>
    bool minimize(T &a, const T &b) {
        if (a > b) return a = b, true;
        return false;
    }

template<class T>
    bool maximize(T &a, const T &b) {
        if (a < b) return a = b, true;
        return false;
    }

#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "icebear"

const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 100000 + 5;
const int S = 1000;
int n, m, q;
array<int, 3> tmp[N], queries[N];

struct DSU {
    int lab[N];
    vector<array<int, 4>> history;

    void reset() {
        memset(lab, -1, sizeof lab);
    }

    void del_history() {
        history.clear();
    }

    int root(int v) {
        return (lab[v] < 0 ? v : root(lab[v]));
    }

    bool unite(int u, int v) {
        u = root(u); v = root(v);
        if (u == v) return false;
        if (lab[u] > lab[v]) swap(u, v);
        history.pb({u, lab[u], v, lab[v]});
        lab[u] += lab[v];
        lab[v] = u;
        return true;
    }

    void roll_back() {
        while(!history.empty()) {
            auto T = history.back();
            lab[T[0]] = T[1];
            lab[T[2]] = T[3];
            history.pop_back();
        }
    }

    int sz(int x) {
        x = root(x);
        return -lab[x];
    }
} dsu;

void init(void) {
    cin >> n >> m;
    FOR(i, 1, m) REP(j, 3) cin >> tmp[i][j];
    cin >> q;
    FOR(i, 1, q) REP(j, 3) cin >> queries[i][j];
}

void process(void) {
    vector<bool> change(m + 5, false);
    vector<int> ans(q + 5, -1), firstVal(m + 5, -1);
    for(int B = 1; B <= q; B += S) {
        int L = B, R = min(q, B + S - 1);
        vector<array<int, 3>> Q, edges;
        vector<ii> indexs;

        FOR(i, L, R) if (queries[i][0] == 1) {
            indexs.pb(mp(queries[i][1], i));
            change[queries[i][1]] = true;
        } else {
            Q.push_back({queries[i][1], queries[i][2], i});
        }

        FOR(i, 1, m) if (change[i] == false)
            edges.pb(tmp[i]);

        sort(all(edges), [&](const array<int, 3> &x, const array<int, 3> &y){
            return x[2] > y[2];
        });

        sort(all(Q), [&](const array<int, 3> &x, const array<int, 3> &y){
            return x[1] > y[1];
        });

        dsu.reset();
        int j = 0;
        for(auto &x : Q) {
            while(j < (int)edges.size() && edges[j][2] >= x[1]) {
                dsu.unite(edges[j][0], edges[j][1]);
                j++;
            }
            dsu.del_history();

            for(auto &e : indexs) {
                if (e.se > x[2]) break;
                if (firstVal[e.fi] == -1)
                    firstVal[e.fi] = tmp[e.fi][2];
                tmp[e.fi][2] = queries[e.se][2];
            }

            for(auto &e : indexs) {
                if (tmp[e.fi][2] >= x[1])
                    dsu.unite(tmp[e.fi][0], tmp[e.fi][1]);
            }

            for(auto &e : indexs) if (firstVal[e.fi] != -1) {
                tmp[e.fi][2] = firstVal[e.fi];
                firstVal[e.fi] = -1;
            }

            ans[x[2]] = dsu.sz(x[0]);
            dsu.roll_back();
        }

        for(auto &e : indexs) {
            change[e.fi] = false;
            tmp[e.fi][2] = queries[e.se][2];
        }
    }

    for(int &x : ans) if (x != -1)
        cout << x << '\n';
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int tc = 1;
//     cin >> tc;
    while(tc--) {
        init();
        process();
    }
    return 0;
}

Compilation message (stderr)

bridges.cpp: In function 'int main()':
bridges.cpp:160:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  160 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
bridges.cpp:161:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  161 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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