Submission #245764

#	Time	Username	Problem	Language	Result	Execution time	Memory
245764		icypiggy	Bridges (APIO19_bridges)	C++14	100 / 100	1390 ms	15712 KiB

bridges

#include <bits/stdc++.h>
 
using namespace std;
int n,m,qc;
const int n_max = 5e4+10;
const int m_max = 1e5+10;
const int q_max = 1e5+10;
struct edge {
    int u,v,w,s,e;
    edge() : u(0), v(0), w(0), s(0), e(0) {}
    edge(int _u, int _v, int _w, int _s, int _e) : u(_u), v(_v), w(_w), s(_s), e(_e) {}
    bool operator < (edge other) const {
        return w > other.w; // invert comparator
    }
};
struct query {
    int time, start, weight, ans;
    query() : time(0), start(0), weight(0), ans(0) {}
    query(int _t, int _s, int _w) : time(_t), start(_s), weight(_w), ans(0) {}
    bool operator < (query other) const {
        return weight > other.weight;
    }
};
vector<query> q;
vector<edge> init[m_max];
vector<edge> sorted_edge;
int visited[n_max];
int parent[n_max];
int sz[n_max];
// reset the ufds
void reset_ufds() {
    for(int i=0; i<n_max; i++) {
        parent[i] = i;
        sz[i] = 1;
    }
}
int findset(int x) {
    while(parent[x]!=x) {
        x = parent[x] = parent[parent[x]];
    }
    return x;
}
void onion(int x, int y) {
    x = findset(x);
    y = findset(y);
    if(x!=y) {
        if(sz[x]>sz[y]) swap(x,y);
        sz[y] += sz[x];
        parent[x] = y;
    }
}
vector<int> adj[n_max];
vector<pair<int,int>> output;
void ans_query(int first, int last) { // [first,last)
    for(int i=0; i<n_max; i++) {
        adj[i].clear();
    }
    if(first>=last) return;
    reset_ufds();
    int ts = q[first].time;
    int te = q[last-1].time;
    sort(q.begin()+first, q.begin()+last); // sort by weight
    auto it = sorted_edge.begin();
    vector<edge> templist;
    for(int i=first; i<last; i++) {
        //cout << "i: " << i << "\n";
        //cout << q[i].time << " " << q[i].weight << "\n";
        while(it!=sorted_edge.end() && it->w >= q[i].weight) {
            //it->print();
            //cout << "weight: " << it->w << " " << it->s << " " << it->e << "\n";
            if(it->s < ts && it->e > te) {
                onion(it->u, it->v);
            } else if((it->s < te && it->s > ts) || (it->e < te && it->e > ts)) {
                // add it to the list of edges to process
                //cout << "templist: " << it->u << " " << it->v << "\n";
                templist.push_back(*it);
            }
            it++;
        }
        int starting = findset(q[i].start);
        int ans = sz[starting];
        for(edge &e: templist) {
            e.u = findset(e.u);
            e.v = findset(e.v);
            adj[e.u].clear();
            adj[e.v].clear();
        }
        for(edge &e: templist) {
            if(e.s < q[i].time && e.e>q[i].time) {
                adj[e.u].push_back(e.v);
                adj[e.v].push_back(e.u);
            }
        }
        visited[starting] = i; // record the visited time
        //cout << "starting: " << starting << "\n";
        queue<int> bfs;
        bfs.push(starting);
        while(!bfs.empty()) {
            int next = bfs.front();
            //cout << "bfs: " << next << "\n";
            bfs.pop();
            for(int z: adj[next]) {
                z = findset(z);
                if(visited[z]!=i) {
                    visited[z] = i;
                    ans += sz[z];
                    bfs.push(z);
                }
            }
        }
        output.push_back(make_pair(q[i].time, ans));
        //cout << "output: " << q[i].time << " " << ans << "\n";
    }
}
int main() {
    //freopen("../q2/05","r",stdin);
    //freopen("05b","w",stdout);
    cin>>n>>m;
    for(int i=0; i<m; i++) {
        edge e;
        cin >> e.u >> e.v >> e.w;
        e.s = -1;
        e.e = 2e5;
        init[i].push_back(e);
    }
    cin >> qc;
    const int bucket_size = 500;
    vector<int> breakpoints;
    for(int i=0; i<qc; i++) {
        if(i%bucket_size==0) breakpoints.push_back(q.size());
        int a,b,c; cin>>a>>b>>c;
        if(a==2) {
            q.push_back(query(i, b, c));
        } else {
            assert(a==1);
            init[b-1].back().e = i;
            init[b-1].push_back(edge(init[b-1][0].u, init[b-1][0].v, c, i, 2e5));
        }
    }
    for(int i=0; i<m; i++) {
        for(edge e: init[i]) {
            sorted_edge.push_back(e);
        }
    }
    breakpoints.push_back(q.size());
    sort(sorted_edge.begin(), sorted_edge.end());
 
    memset(visited, -1, sizeof(visited));
    for(int i=1; i<breakpoints.size(); i++) {
        //cout << "?\n";
        ans_query(breakpoints[i-1], breakpoints[i]);
    }
    sort(output.begin(), output.end());
    for(int i=1; i<output.size(); i++) {
        assert(output[i].first != output[i-1].first);
    }
    for(auto p: output) {
        cout << p.second << "\n";
    }
    return 0;
}

Compilation message (stderr)

bridges.cpp: In function 'int main()':
bridges.cpp:149:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1; i<breakpoints.size(); i++) {
                  ~^~~~~~~~~~~~~~~~~~~
bridges.cpp:154:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1; i<output.size(); 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