Submission #1212250

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212250		StefanSebez	Joker (BOI20_joker)	C++20	100 / 100	218 ms	9344 KiB

Joker

#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
const int N=2e5+50;
pair<int,int>edges[N];
struct DSU{
	int par[N+50],sajz[N+50],bit[N+50];
	int bip;
	vector<array<int,4>>undo;
	DSU(){Clear();}
	int FS(int u){if(!par[u])return u;return FS(par[u]);}
	int Get(int u){if(!par[u])return 0;return bit[u]^Get(par[u]);}
    void US(int u,int v){
    	int x=Get(u)^Get(v)^1;
    	u=FS(u),v=FS(v);
    	if(u!=v){
			if(sajz[u]>sajz[v]) swap(u,v);
			par[u]=v;
			sajz[v]+=sajz[u];
			bit[u]=x;
			undo.pb({u,v,x,0});
			return;
    	}
		bip+=x;
		undo.pb({0,0,0,x});
    }
    void Undo(){
    	array<int,4>a=undo.back();undo.pop_back();
    	bip-=a[3];
    	if(a[0]==0) return;
		par[a[0]]=0;
		sajz[a[1]]-=sajz[a[0]];
		bit[a[0]]=0;
    }
    void Clear(){for(int i=0;i<=N;i++){par[i]=bit[i]=0;sajz[i]=1;}bip=0;undo.clear();}
}dsu;
int desno[N];
void Solve(int l,int r,int lo,int up){
	if(l>r) return;
	int mid=l+r>>1;
	//printf("%i %i %i %i %i\n",l,mid,r,lo,up);
	int cnt1=0,cnt2=0;
	for(int i=l;i<mid;i++) dsu.US(edges[i].fi,edges[i].se),cnt1++;
    for(int i=up;i>=max(mid,lo);i--){
		if(dsu.bip>0){desno[mid]=i;break;}
		dsu.US(edges[i].fi,edges[i].se),cnt2++;
    }
    while(cnt2--) dsu.Undo();
    while(cnt1--) dsu.Undo();
    if(desno[mid]==0) desno[mid]=mid-1;

	for(int i=up;i>desno[mid];i--) dsu.US(edges[i].fi,edges[i].se);
	Solve(l,mid-1,lo,desno[mid]);
	for(int i=up;i>desno[mid];i--) dsu.Undo();

	for(int i=l;i<=mid;i++) dsu.US(edges[i].fi,edges[i].se);
	Solve(mid+1,r,desno[mid],up);
	for(int i=l;i<=mid;i++) dsu.Undo();
}
int main(){
    int n,m,q;scanf("%i%i%i",&n,&m,&q);
    for(int i=1,u,v;i<=m;i++){
		scanf("%i%i",&u,&v);
		edges[i]={u,v};
    }
    Solve(1,m,1,m);
    //for(int i=1;i<=m;i++) printf("%i: %i\n",i,desno[i]);
    while(q--){
		int l,r;scanf("%i%i",&l,&r);
		if(r<=desno[l]) printf("YES\n");
		else printf("NO\n");
    }
    return 0;
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:65:20: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     int n,m,q;scanf("%i%i%i",&n,&m,&q);
      |               ~~~~~^~~~~~~~~~~~~~~~~~~
Joker.cpp:67:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |                 scanf("%i%i",&u,&v);
      |                 ~~~~~^~~~~~~~~~~~~~
Joker.cpp:73:30: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |                 int l,r;scanf("%i%i",&l,&r);
      |                         ~~~~~^~~~~~~~~~~~~~

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