Submission #990652

#	Time	Username	Problem	Language	Result	Execution time	Memory
990652		imarn	Joker (BOI20_joker)	C++14	100 / 100	247 ms	21176 KiB

Joker

#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,ll>
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
const int mxn=4e5+5;
vector<pii>edge;
int pr[mxn]{0},m,n;
int dp[mxn]{0};
int sz[mxn]{0};
stack<pii>st;
void rollback(int x){
    while(st.size()>x){
        pr[st.top().f]=st.top().f;
        sz[st.top().s]-=sz[st.top().f];
        st.pop();
    }
}
int get(int r){
    return pr[r]==r?r:get(pr[r]);
}
void uni(int a,int b){
    a=get(a),b=get(b);
    if(a==b)return;
    if(sz[a]>sz[b])swap(a,b);
    pr[a]=b;sz[b]+=sz[a];
    st.push({a,b});
}
void solve(int l1,int r1,int l2,int r2){
    if(l1>r1)return;
    int md=(l1+r1)>>1,md2=-1;
    int pv1=st.size();
    for(int i=l1;i<=md-1;i++){
        uni(edge[i-1].f,edge[i-1].s+n);
        uni(edge[i-1].f+n,edge[i-1].s);
    }int pv2=st.size();
    for(int i=r2;i>=max(l2,md);i--){
        uni(edge[i-1].f,edge[i-1].s+n);
        uni(edge[i-1].f+n,edge[i-1].s);
        if(get(edge[i-1].f)==get(edge[i-1].f+n)||get(edge[i-1].s)==get(edge[i-1].s+n)){md2=i;break;}
    }if(md2==-1)md2=md-1;
    dp[md]=md2;rollback(pv2);uni(edge[md-1].f,edge[md-1].s+n);
    uni(edge[md-1].f+n,edge[md-1].s);
    solve(md+1,r1,md2,r2);
    rollback(pv1);
    for(int i=r2;i>=md2+1;i--){
        uni(edge[i-1].f,edge[i-1].s+n);
        uni(edge[i-1].f+n,edge[i-1].s);
    }
    solve(l1,md-1,l2,md2);rollback(pv1);
}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int q;cin>>n>>m>>q;iota(pr,pr+2*n+1,0);
    for(int i=1;i<=2*n;i++)sz[i]=1;
    for(int i=0;i<m;i++){
        int u,v;cin>>u>>v;
        edge.pb({u,v});
    }solve(1,m,1,m);bool ok=0;
    for(int i=1;i<=m;i++){
        if(ok)dp[i]=m+1;
        uni(edge[i-1].f+n,edge[i-1].s);
        uni(edge[i-1].f,edge[i-1].s+n);
        if(get(edge[i-1].f)==get(edge[i-1].f+n)||get(edge[i-1].s)==get(edge[i-1].s+n))ok=1;
    }
    while(q--){
        int l,r;cin>>l>>r;
        cout<<(r<dp[l]?"YES\n":"NO\n");
    }
}

Compilation message (stderr)

Joker.cpp: In function 'void rollback(int)':
Joker.cpp:16:20: warning: comparison of integer expressions of different signedness: 'std::stack<std::pair<int, long long int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   16 |     while(st.size()>x){
      |           ~~~~~~~~~^~

• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 25 / 25
• Subtask 4: 10 / 10
• Subtask 5: 22 / 22
• Subtask 6: 29 / 29