Submission #581001

#	Time	Username	Problem	Language	Result	Execution time	Memory
581001		juggernaut	Event Hopping (BOI22_events)	C++14	40 / 100	1588 ms	99276 KiB

events

#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
typedef long long ll;
typedef long double ld;
#define USING_ORDERED_SET 0
#if USING_ORDERED_SET
#include<bits/extc++.h>
using namespace __gnu_pbds;
template<class T>using ordered_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#endif
template<class T>void umax(T &a,T b){if(a<b)a=b;}
template<class T>void umin(T &a,T b){if(b<a)a=b;}
#ifdef juggernaut
    #define printl(args...) printf(args)
#else
    #define printl(args...) 0
#endif
int n,q;
pair<int,int>a[100005];
bool cmp(pair<pair<int,int>,int>l,pair<pair<int,int>,int>r){
	if(l.fr.sc==r.fr.sc)return l.fr.fr<r.fr.fr;
	return l.fr.sc<r.fr.sc;
}
int dp[5005][5005];
int lf[100005];
pair<pair<int,int>,int>b[100005];
const int inf=1e9;
int pos[100005];
int fen[100005];
void update(int pos,int val){
	while(pos<=n+2){
		umin(fen[pos],val);
		pos+=(pos&-pos);
	}
}
int query(int pos){
	int ans=inf;
	while(pos){
		umin(ans,fen[pos]);
		pos-=(pos&-pos);
	}
	return ans;
}
int dp2[100005];
int main(){
	scanf("%d%d",&n,&q);
	for(int i=1;i<=n;i++)scanf("%d%d",&a[i].fr,&a[i].sc);
	for(int i=1;i<=n;i++)b[i]=make_pair(a[i],i);
	sort(b+1,b+1+n,cmp);
	for(int i=1;i<=n;i++)pos[b[i].sc]=i;
	for(int i=1;i<=n;i++){
		int l=1,r=i;
		while(l<r){
			int mid=(l+r)>>1;
			if(b[i].fr.fr<=b[mid].fr.sc)r=mid;
			else l=mid+1;
		}
		lf[i]=l;
	}
	if(n<=5000){
		for(int i=0;i<5005;i++)
		for(int j=0;j<5005;j++)dp[i][j]=inf;
		for(int i=1;i<=n;i++){
			dp[i][i]=0;
			for(int j=1;j<=n+2;j++)fen[j]=inf;
			update(n-i+1,0);
			for(int j=i+1;j<=n;j++){
				dp[i][j]=query(n-lf[j]+1)+1;
				//for(int k=lf[j];k<=n;k++)umin(dp[i][j],dp[i][k]+1);
				update(n-j+1,dp[i][j]);
			}
		}
		while(q--){
			int x,y;
			scanf("%d%d",&x,&y);
			if(x==y){
				puts("0");
				continue;
			}
			if(a[y].fr<=a[x].sc&&a[x].sc<=a[y].sc){
				puts("1");
				continue;
			}
			if(dp[pos[x]][pos[y]]>=inf)puts("impossible");
			else printf("%d\n",dp[pos[x]][pos[y]]);
		}
		return 0;
	}else{
		while(q--){
			int x,y;
			scanf("%d%d",&x,&y);
			if(x==y){
				puts("0");
				continue;
			}
			if(a[y].fr<=a[x].sc&&a[x].sc<=a[y].sc){
				puts("1");
				continue;
			}
			x=pos[x];
			y=pos[y];
			for(int i=1;i<=n;i++)dp2[i]=inf;
			dp2[x]=0;
			for(int j=1;j<=n+2;j++)fen[j]=inf;
			update(n-x+1,0);
			for(int j=x+1;j<=y;j++){
				dp2[j]=query(n-lf[j]+1)+1;
				update(n-j+1,dp2[j]);
			}
			if(dp2[y]>=inf)puts("impossible");
			else printf("%d\n",dp2[y]);
		}
		return 0;
	}
	return 1;
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:48:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |  scanf("%d%d",&n,&q);
      |  ~~~~~^~~~~~~~~~~~~~
events.cpp:49:28: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |  for(int i=1;i<=n;i++)scanf("%d%d",&a[i].fr,&a[i].sc);
      |                       ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:77:9: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   77 |    scanf("%d%d",&x,&y);
      |    ~~~~~^~~~~~~~~~~~~~
events.cpp:93:9: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |    scanf("%d%d",&x,&y);
      |    ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30