Submission #979477

#	Time	Username	Problem	Language	Result	Execution time	Memory
979477		nnin	Bridges (APIO19_bridges)	C++17	100 / 100	1490 ms	18500 KiB

bridges

#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define pip pair<int,pii>
#define f first
#define s second

int n, m, q;
vector<pip> edges, query;
vector<pii> bridge[1005];
int ans[100005], part = 1000;
bool change[100005];
vector<pii> ord;

int dsu[50005], sz[50005];
int par(int x) {
    if(dsu[x]==x) return x;
    return par(dsu[x]);
}
void init() {
    for(int i=1;i<=n;i++) {
        dsu[i] = i;
        sz[i] = 1;
    }
    for(int i=0;i<m;i++) {
        change[i] = 0;
    }
    ord.clear();
}
void join(int a, int b) {
    int pa = par(a);
    int pb = par(b);
    if(pa==pb) return;
    if(sz[pa]<sz[pb]) swap(pa, pb);
    ord.push_back({pa, pb});
    dsu[pb] = pa;
    sz[pa] += sz[pb];
}
void undo(int szz) {
    while(ord.size()>szz) {
        auto [pa, pb] = ord.back();
        ord.pop_back();
        sz[pa] -= sz[pb];
        dsu[pb] = pb;
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    cin>>n>>m;
    for(int i=0;i<m;i++) {
        int u, v, w;
        cin>>u>>v>>w;
        edges.push_back({w, {u, v}});
    }
    cin>>q;
    for(int i=0;i<q;i++) {
        int t, x, y;
        cin>>t>>x>>y;
        if(t==1) x--;
        query.push_back({t, {x, y}});
    }
    for(int st=0;st<q;st+=part) {
        int en = min(st+part, q);
        init();
        vector<pip> qu, ed;
        vector<int> one;
        for(int i=st;i<en;i++) {
            if(query[i].f==1) {
                change[query[i].s.f] = 1;
                one.push_back(i);
            } else {
                qu.push_back({query[i].s.s, {query[i].s.f, i}});
            }
        }
        for(int i=0;i<m;i++) {
            if(!change[i]) {
                ed.push_back(edges[i]);
            }
        }
        cout<<'\n';
        for(int i=st;i<en;i++) {
            if(query[i].f==1) {
                edges[query[i].s.f].f = query[i].s.s;
            } else {
                bridge[i-st].clear();
                for(int q:one) {
                    if(edges[query[q].s.f].f>=query[i].s.s) bridge[i-st].push_back(edges[query[q].s.f].s);
                }
            }
        }
        sort(qu.begin(), qu.end());
        sort(ed.begin(), ed.end());
        int e = ed.size()-1;
        for(int i=qu.size()-1;i>=0;i--) {
            int w = qu[i].f;
            int land = qu[i].s.f;
            int idx = qu[i].s.s;
            while(e>=0 && ed[e].f>=w) {
                join(ed[e].s.f, ed[e].s.s);
                e--;
            }
            int szz = ord.size();
            for(pii p:bridge[idx-st]) {
                join(p.f, p.s);
            }
            ans[idx] = sz[par(land)];
            undo(szz);
        }
    }
    for(int i=0;i<q;i++) if(query[i].f==2) cout<<ans[i]<<'\n';
}

Compilation message (stderr)

bridges.cpp: In function 'void undo(int)':
bridges.cpp:40:21: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   40 |     while(ord.size()>szz) {
      |           ~~~~~~~~~~^~~~

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