Submission #679520

#	Time	Username	Problem	Language	Result	Execution time	Memory
679520		jamezzz	Event Hopping (BOI22_events)	C++17	100 / 100	153 ms	40256 KiB

events

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#define dbg(...) printf(__VA_ARGS__);
#define getchar_unlocked getchar
#else
#define dbg(...)
#endif
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define psf push_front
#define ppb pop_back
#define ppf pop_front
#define sz(x) (int)x.size()
#define mnto(x,y) x=min(x,(__typeof__(x))y)
#define mxto(x,y) x=max(x,(__typeof__(x))y)
#define INF 1023456789
#define LINF 1023456789123456789
#define all(x) x.begin(),x.end()
#define lb(x,v) (lower_bound(all(x),v)-x.begin())
#define ub(x,v) (upper_bound(all(x),v)-x.begin())
#define disc(x) sort(all(x));x.resize(unique(all(x))-x.begin());
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> iii;
typedef tuple<int,int,int,int> iiii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
mt19937 rng(time(0));

#define mod 1000000007

inline int add(int a,int b){
	int r=a+b;
	while(r>=mod)r-=mod;
	while(r<0)r+=mod;
	return r;
}

inline int mult(int a,int b){
	return (int)(((ll)(a*b))%mod);
}

inline int rd(){
	int x=0;
	char ch=getchar_unlocked();
	while(!(ch&16))ch=getchar();//keep reading while current character is whitespace
    while(ch&16){//this will break when ‘\n’ or ‘ ‘ is encountered
		x=(x<<3)+(x<<1)+(ch&15);
		ch=getchar_unlocked();
	}
	return x;
}

#define maxn 100005

int n,q,m,s[maxn],e[maxn],p[20][maxn];
ii st[20][2*maxn];
vector<int> d;

inline ii qmn(int l,int r){
	int k=31-__builtin_clz(r-l+1);
	return min(st[k][l],st[k][r-(1<<k)+1]);
}

int main(){
	sf("%d%d",&n,&q);
	for(int i=0;i<n;++i){
		sf("%d%d",&s[i],&e[i]);
		d.pb(s[i]);d.pb(e[i]);
	}
	disc(d);
	for(int i=0;i<n;++i){
		s[i]=lb(d,s[i]);
		e[i]=lb(d,e[i]);
	}
	m=sz(d);
	for(int i=0;i<m;++i)st[0][i]={INF,-1};
	for(int i=0;i<n;++i)mnto(st[0][e[i]],ii(s[i],i));
	for(int k=1;k<20;++k){
		for(int i=0;i+(1<<k)<=m;++i){
			st[k][i]=min(st[k-1][i],st[k-1][i+(1<<k-1)]);
		}
	}
	
	for(int i=0;i<n;++i)p[0][i]=qmn(s[i],e[i]).se;
	for(int k=0;k<19;++k){
		for(int i=0;i<n;++i){
			if(p[k][i]==-1)p[k+1][i]=-1;
			else p[k+1][i]=p[k][p[k][i]];
		}
	}
	
	for(int i=0;i<q;++i){
		int x,y;sf("%d%d",&x,&y);
		if(x==y){
			pf("0\n");
			continue;
		}
		--x,--y;
		if(e[y]<e[x]){
			pf("impossible\n");
			continue;
		}
		if(s[y]<=e[x]){
			pf("1\n");
			continue;
		}
		int cur=y,ans=0;
		for(int k=19;k>=0;--k){
			int pcur=p[k][cur];
			if(pcur!=-1&&e[x]<s[pcur]){
				cur=pcur;
				ans+=1<<k;
			}
		}
		int pcur=p[0][cur];
		if(pcur==-1||e[x]<s[pcur]){
			pf("impossible\n");
		}
		else pf("%d\n",ans+2);
	}
}

/*
10 10
0 1
1 5
2 4
3 5
5 8
6 8
6 7
7 10
9 11
5 12
*/

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:89:43: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   89 |    st[k][i]=min(st[k-1][i],st[k-1][i+(1<<k-1)]);
      |                                          ~^~
events.cpp:74:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |  sf("%d%d",&n,&q);
      |    ^
events.cpp:76:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |   sf("%d%d",&s[i],&e[i]);
      |     ^
events.cpp:102:13: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |   int x,y;sf("%d%d",&x,&y);
      |             ^

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