Submission #1070481

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070481		Thanhs	Bridges (APIO19_bridges)	C++14	100 / 100	2906 ms	10464 KiB

bridges

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
// #define int long long
// #define double long double
 
#define endl '\n'
#define fastIO ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define setmin(x, y) x = min((x), (y))
#define setmax(x, y) x = max((x), (y))
#define sqr(x) ((x) * (x))
#define fi first
#define se second
#define all(x) x.begin(), x.end()
 
// mt19937 hdp(chrono::high_resolution_clock::now().time_since_epoch().count());
// int rand(int l, int r){return l + ((hdp() % (r - l + 1)) + r - l + 1) % (r - l + 1);}

const int NM = 1e5 + 5;
const int SQ = 320;

struct Query
{
    int a, b, c;
    Query(int _a, int _b, int _c) : a(_a), b(_b), c(_c){}
};
vector<Query> Q;

struct Edge
{
    int u, v, w;
    Edge(){}
}e[NM];

struct DSU
{ 
    int p[NM];
    vector<pair<int, int>> c;
    DSU() {memset(p, -1, sizeof p);}
    void init(int n) {memset(p, -1, (n + 1) * (sizeof p[0])); c.clear();}
    int find(int u) {return p[u] < 0 ? u : find(p[u]);}
    void join(int u, int v, int save)
    {
        u = find(u), v = find(v);
        if (save)
            c.emplace_back(-1, -1);
        if (u == v)
            return;
        if (save)
            c.emplace_back(u, p[u]);
            c.emplace_back(v, p[v]);
        if (p[u] > p[v])
            swap(u, v);
        p[u] += p[v];
        p[v] = u;
    }
    void rollback()
    {
        while (~c.back().fi)
        {
            p[c.back().fi] = c.back().se;
            c.pop_back();
        }
        c.pop_back();
    }
}dsu;

vector<pair<int, int>> ans;
int cur, n, m, q, mp[NM];
bool o[NM];

void giai()
{
    dsu.init(n);
    vector<int> id;
    vector<Query> QQ, E;
    vector<Edge> T;
    for (auto t : Q)
    {
        if (t.a == 1)
        {
            if (!o[t.b])
                id.push_back(t.b);
            o[t.b] = 1;
            E.emplace_back(t.c, t.b, ++cur);
        }
        else
            QQ.emplace_back(t.c, t.b, ++cur);
    }
    for (int i = 1; i <= m; i++)
        if (!o[i])
            T.emplace_back(e[i]);
    sort(QQ.begin(), QQ.end(), [&](auto x, auto y){return x.a > y.a;});
    sort (T.begin(), T.end(), [&](auto x, auto y){return x.w > y.w;});
    int pt = 0;
    for (auto t : QQ)
    {
        while (pt < T.size() && T[pt].w >= t.a)
        {
            dsu.join(T[pt].u, T[pt].v, 0);
            pt++;
        }
        int cnt = 0;
        for (auto ee : E)
        {
            if (ee.c < t.c)
                mp[ee.b] = ee.a;
            if (!mp[ee.b])
                mp[ee.b] = e[ee.b].w;
        }
        for (auto i : id)
            if (mp[i] >= t.a)
            {
                dsu.join(e[i].u, e[i].v, 1);
                cnt++;
            }
        for (auto i : id)
            mp[i] = 0;
        ans.emplace_back(t.c, -dsu.p[dsu.find(t.b)]);
        while (cnt--)
            dsu.rollback();
    }
    for (auto t : Q)
        if (t.a == 1)
        {
            e[t.b].w = t.c;
            o[t.b] = 0;
        }
    Q.clear();
}

void pre()
{
}

void solve()
{
    pre();
    cin >> n >> m;
    for (int i = 1; i <= m; i++)
        cin >> e[i].u >> e[i].v >> e[i].w;
    cin >> q;
    for (int i = 1; i <= q; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        Q.emplace_back(a, b, c);
        if (Q.size() == SQ)
            giai();
    }
    if (Q.size())
        giai();
    sort(ans.begin(), ans.end());
    for (auto t : ans)
        cout << t.se << endl;
}

signed main()
{
    fastIO
    if (fopen("in.txt", "r")) 
    {
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    }
    int tc = 1;
    // cin >> tc;
    while (tc--)
        solve();
}

Compilation message (stderr)

bridges.cpp: In member function 'void DSU::join(int, int, int)':
bridges.cpp:50:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   50 |         if (save)
      |         ^~
bridges.cpp:52:13: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   52 |             c.emplace_back(v, p[v]);
      |             ^
bridges.cpp: In function 'void giai()':
bridges.cpp:99:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Edge>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   99 |         while (pt < T.size() && T[pt].w >= t.a)
      |                ~~~^~~~~~~~~~
bridges.cpp: In function 'int main()':
bridges.cpp:164:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  164 |         freopen("in.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
bridges.cpp:165:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  165 |         freopen("out.txt", "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