Submission #623013

#	Time	Username	Problem	Language	Result	Execution time	Memory
623013		tamthegod	Bridges (APIO19_bridges)	C++14	100 / 100	2193 ms	125624 KiB

bridges

#include<bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, m;
int block_size = 1000;
int mark[maxN];
int lab[maxN];
int res[maxN];
vector<pair<int, int>> vc;
int Findset(int u)
{
    return lab[u] < 0 ? u : Findset(lab[u]);
}
void Unite(int u, int v)
{
    int r = Findset(u), s = Findset(v);
    if(r == s)
        return;
    if(lab[r] > lab[s])
        swap(r, s);
    vc.pb({r, lab[r]});
    vc.pb({s, lab[s]});
    lab[r] += lab[s];
    lab[s] = r;
}
void roll_back(int sz)
{
    while(vc.size() > sz)
    {
        pair<int, int> tmp = vc.back();
        vc.pop_back();
        lab[tmp.fi] = tmp.se;
    }
}
struct TEdge
{
    int u, v, w;
} e[maxN];
int q;
struct TQuery
{
    int type;
    int s, w;
} qu[maxN];
vector<int> upd[maxN];
void ReadInput()
{
    cin >> n >> m;
    for(int i=1; i<=m; i++)
    {
        int u, v, w;
        cin >> u >> v >> w;
        e[i] = {u, v, w};
    }
    cin >> q;
    for(int i=1; i<=q; i++)
    {
        cin >> qu[i].type >> qu[i].s >> qu[i].w;
    }
}
void Solve()
{
    for(int i=1; i<=block_size; i++)
    {
        memset(lab, -1, sizeof lab);
        vc.clear();
        int l = block_size * (i - 1) + 1, r = min(q, block_size * i);
        if(l > q)
            break;
        for(int j=1; j<=m; j++)
            mark[j] = 0;
        for(int j=l; j<=r; j++)
        {
            if(qu[j].type == 1)
            {
                mark[qu[j].s] = 1;
            }
        }
        vector<int> unchanged, query, changed;
        for(int j=1; j<=m; j++)
        {
            if(!mark[j])
                unchanged.pb(j);
            else
                changed.pb(j);
        }
        for(int j=l; j<=r; j++)
            if(qu[j].type == 2)
                query.pb(j);
        for(int j=l; j<=r; j++)
        {
            if(qu[j].type == 1)
                e[qu[j].s].w = qu[j].w;
            else
            {
                for(int v : changed)
                    if(e[v].w >= qu[j].w)
                        upd[j].pb(v);
            }
        }
        sort(unchanged.begin(), unchanged.end(), [](int i, int j)
        {
            return e[i].w > e[j].w;
        });
        sort(query.begin(), query.end(), [](int i, int j)
        {
            return qu[i].w > qu[j].w;
        });
        int p = 0;
        for(int j : query)
        {
            while(p < unchanged.size() && e[unchanged[p]].w >= qu[j].w)
            {
                Unite(e[unchanged[p]].u, e[unchanged[p]].v);
                p++;
            }
            int sz = vc.size();
            for(int v : upd[j])
            {
               // if(j == 5) cout << v << " ";
                Unite(e[v].u, e[v].v);
            }
            res[j] = -lab[Findset(qu[j].s)];
            roll_back(sz);
        }
    }
    for(int i=1; i<=q; i++)
    {
        if(qu[i].type == 2)
            cout << res[i] << '\n';
    }
}
int32_t main()
{
   // freopen("x.inp", "r", stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ReadInput();
    Solve();
}

Compilation message (stderr)

bridges.cpp: In function 'void roll_back(int)':
bridges.cpp:37:21: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   37 |     while(vc.size() > sz)
      |           ~~~~~~~~~~^~~~
bridges.cpp: In function 'void Solve()':
bridges.cpp:121:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  121 |             while(p < unchanged.size() && e[unchanged[p]].w >= qu[j].w)
      |                   ~~^~~~~~~~~~~~~~~~~~

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