Submission #207404

#	Time	Username	Problem	Language	Result	Execution time	Memory
207404		brcode	Bridges (APIO19_bridges)	C++14	100 / 100	2943 ms	32984 KiB

bridges

#include <iostream>
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5+10;
int  n,m,q;
stack<int> s1;
int sz[MAXN];

int par[MAXN];
void reset(){
    for(int i=1;i<MAXN;i++){
        par[i] = i;
    }
    for(int i=1;i<MAXN;i++){
        sz[i] = 1;
    }
}
int find(int a){
    while(par[a] !=a){
        a=par[a];
    }
    return a;
}
void merge(int a,int b){
    a =find(a);
    b = find(b);
    if(a==b){
        return;
    }
    if(sz[a]>sz[b]){
        swap(a,b);
    }
    s1.push(a);
    sz[b]+=sz[a];
    par[a] =par[b];
}
void rollback(int x){
    while(s1.size()>x){
        int k = s1.top();
        s1.pop();
        sz[par[k]]-=sz[k];
        par[k] = k;
    }
}
int u[MAXN],v[MAXN],w[MAXN],t[MAXN],x[MAXN],y[MAXN];
bool changed[MAXN];
vector<int> to_join[1010];
int ans[MAXN];
bool cmp(int a,int b){
    return y[a]>y[b];
}
bool cmp2(int a,int b){
    return w[a]>w[b];
}
int main(){
    cin>>n>>m;
    for(int i=1;i<=m;i++){
        cin>>u[i]>>v[i]>>w[i];
    }
    cin>>q;
    for(int i=1;i<=q;i++){
        cin>>t[i]>>x[i]>>y[i];
    }
    for(int l=1;l<=q;l+=1000){
        int r = min(q,l+1000-1);
        reset();
        vector<int> ask,update,unchanged;
        for(int i=0;i<=m;i++){
            changed[i] = false;
        }
        for(int i=l;i<=r;i++){
            if(t[i] == 1){
                changed[x[i]]=true;
                update.push_back(i);
            }else{
                ask.push_back(i);
                
            }
        }
        for(int i=1;i<=m;i++){
            if(!changed[i]){
                unchanged.push_back(i);
            }
        }
        for(int i=l;i<=r;i++){
            if(t[i] == 1){
                w[x[i]] = y[i];
            }else{
                to_join[i-l].clear();
                for(int j:update){
                    if(w[x[j]]>=y[i]){
                        to_join[i-l].push_back(x[j]);
                    }
                }
            }    
        }
        sort(ask.begin(),ask.end(),cmp);
        sort(unchanged.begin(),unchanged.end(),cmp2);
        int ptr = 0;
        for(int i:ask){
            while(ptr<unchanged.size() && w[unchanged[ptr]]>=y[i]){
                merge(u[unchanged[ptr]],v[unchanged[ptr]]);
                ptr++;
            }
            int prev_size = s1.size();
            for(int j:to_join[i-l]){
                merge(u[j],v[j]);
            }
            ans[i] = sz[find(x[i])];
            rollback(prev_size);
        }
    }
    for(int i=1;i<=q;i++){
        if(t[i] == 2){
            cout<<ans[i]<<endl;
        }
    }
}

Compilation message (stderr)

bridges.cpp: In function 'void rollback(int)':
bridges.cpp:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(s1.size()>x){
           ~~~~~~~~~^~
bridges.cpp: In function 'int main()':
bridges.cpp:101:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while(ptr<unchanged.size() && w[unchanged[ptr]]>=y[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