Submission #678763

#	Time	Username	Problem	Language	Result	Execution time	Memory
678763		jamezzz	Event Hopping (BOI22_events)	C++17	10 / 100	1588 ms	266648 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,s[maxn],e[maxn];
set<ii> nx[maxn];

int main(){
	sf("%d%d",&n,&q);
	for(int i=0;i<n;++i){
		sf("%d%d",&s[i],&e[i]);
	}
	for(int i=0;i<n;++i){
		for(int j=0;j<n;++j){
			if(i==j)continue;
			if(s[j]<=e[i]&&e[i]<=e[j]){
				nx[i].insert({e[j],j});
			}
		}
	}
	for(int i=0;i<q;++i){
		int l,r;sf("%d%d",&l,&r);
		--l,--r;
		int ans=0;
		while(l!=r){
			if(nx[l].count({e[r],r})){
				++ans;break;
			}
			if(nx[l].empty()||e[r]<(*nx[l].begin()).fi){
				ans=-1;break;
			}
			auto it=--nx[l].upper_bound({e[r],INF});
			if((*it).fi==e[l]){
				ans=-1;break;
			}
			l=(*it).se;++ans;
		}
		if(ans!=-1)pf("%d\n",ans);
		else pf("impossible\n");
	}
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:68:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |  sf("%d%d",&n,&q);
      |    ^
events.cpp:70:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |   sf("%d%d",&s[i],&e[i]);
      |     ^
events.cpp:81:13: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |   int l,r;sf("%d%d",&l,&r);
      |             ^

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