# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
896418 | Nexus | Event Hopping (BOI22_events) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <math.h>
#include <string>
#include <algorithm>
#include <random>
#include <iomanip>
#include <utility>
#include <cstring>
//#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll N=1e3+9,M=1e18+9,mod=1e9+7;
//cout<<fixed<<setprecision(6)<<
ll dp[N][N],s[N],e[N],n,q,i,j,k,ans;
bool vis[N];
vector<ll>v[N];
void dfs(ll node,ll num){
if(node==j){
k=1,ans=min(ans,num);
return;
}
if(vis[node])return;
vis[node]=1;
for(auto p:v[node]){
ll g=k;
dfs(p,num+1);
if(!g && k)dp[node,j]=ans-num;
}
vis[node]=0;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>q;
for(i=1;i<=n;++i)cin>>s[i]>>e[i];
for(ll i=1;i<=n;++i){
for(ll j=1;j<=n;++j){
if(s[j]<=e[i] && e[i]<=e[j])
v[i].push_back(j);
}
}
while(q--){
cin>>i>>j;
k=0,ans=M;
if(dp[i][j])cout<<dp[i][j]<<'\n';else{
dfs(i,0);
if(k)cout<<ans<<'\n';
else cout<<"impossible\n";}
}
}