#include<bits/stdc++.h>
using namespace std;
const int MAXN=3e4+2;
const int INF=2e9;
int n,m;
struct doge
{
int p,pos;
bool operator<(const doge& other)
{
if(pos!=other.pos)return pos<other.pos;
return p<=other.p;
}
}d[MAXN];
struct state
{
int pos,p,d;
bool operator<(state const& other)const
{
if(d!=other.d)return d>other.d;
return make_pair(p,pos)<make_pair(other.p,other.pos);
}
};
set<pair<int,int> >doges;
set<int>doges1[MAXN];
vector<int>states;
unordered_map<int,int>dist;
int main()
{
srand(654);
int e=rand();
ios_base::sync_with_stdio(nullptr);
cin.tie(NULL);
cout.tie(NULL);
cin>>n>>m;
for(int i=0;i<m;++i)
{
cin>>d[i].pos>>d[i].p;
doges.insert({d[i].p,d[i].pos%d[i].p});
doges1[d[i].pos].insert(d[i].p);
}
for(auto t:doges)
{
for(int i=t.second;i<n;i+=t.first)
{
states.push_back(i*MAXN+t.first);
}
}
dist.reserve(states.size());
for(auto s:states)
{
dist[(s^e)]=INF;
}
priority_queue<state>pq;
pq.push({d[0].pos,d[0].p,0});
dist[(d[0].pos*MAXN+d[0].p)^e]=0;
while(!pq.empty())
{
state u=pq.top();pq.pop();
if(dist[(u.pos*MAXN+u.p)^e]<u.d)continue;
if(u.pos==d[1].pos&&u.p==d[1].p)break;
//cout<<u.pos<<" "<<u.p<<endl;
if(doges1[u.pos].size()>0)
{
auto it=doges1[u.pos].lower_bound(u.p);
if(it!=doges1[u.pos].end()&&(*it)!=u.p)
{
auto d1=(*it);
if(dist[(u.pos*MAXN+d1)^e]>u.d)
{
dist[(u.pos*MAXN+d1)^e]=u.d;
pq.push({u.pos,d1,u.d});
}
}
if(it!=doges1[u.pos].begin())
{
--it;
auto d1=(*it);
if(dist[(u.pos*MAXN+d1)^e]>u.d)
{
dist[(u.pos*MAXN+d1)^e]=u.d;
pq.push({u.pos,d1,u.d});
}
++it;
}
//cout<<"**\n";
if(it!=doges1[u.pos].end())++it;
if(it!=doges1[u.pos].end())
{
auto d1=(*it);
if(dist[(u.pos*MAXN+d1)^e]>u.d)
{
dist[(u.pos*MAXN+d1)^e]=u.d;
pq.push({u.pos,d1,u.d});
}
}
}
//cout<<"***\n";
/*for(auto d1:doges1[u.pos])
{
if(dist[(u.pos*MAXN+d1)^e]>u.d)
{
dist[(u.pos*MAXN+d1)^e]=u.d;
pq.push({u.pos,d1,u.d});
}
}*/
state v=u;
if(v.pos+v.p<n)
{
v.pos+=v.p;
if(dist[(v.pos*MAXN+v.p)^e]>u.d+1)
{
v.d=u.d+1;
dist[(v.pos*MAXN+v.p)^e]=v.d;
pq.push(v);
}
}
v=u;
if(v.pos-v.p>=0)
{
v.pos-=v.p;
if(dist[(v.pos*MAXN+v.p)^e]>u.d+1)
{
v.d=u.d+1;
dist[(v.pos*MAXN+v.p)^e]=v.d;
pq.push(v);
}
}
}
if(dist[(d[1].pos*MAXN+d[1].p)^e]==INF)
{
cout<<-1<<"\n";
}
else cout<<dist[(d[1].pos*MAXN+d[1].p)^e]<<"\n";
return 0;
}
Compilation message
skyscraper.cpp: In function 'int main()':
skyscraper.cpp:32:28: error: converting to 'bool' from 'std::nullptr_t' requires direct-initialization [-fpermissive]
32 | ios_base::sync_with_stdio(nullptr);
| ^~~~~~~
In file included from /usr/include/c++/9/ios:42,
from /usr/include/c++/9/istream:38,
from /usr/include/c++/9/sstream:38,
from /usr/include/c++/9/complex:45,
from /usr/include/c++/9/ccomplex:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:54,
from skyscraper.cpp:1:
/usr/include/c++/9/bits/ios_base.h:747:26: note: initializing argument 1 of 'static bool std::ios_base::sync_with_stdio(bool)'
747 | sync_with_stdio(bool __sync = true);
| ~~~~~^~~~~~~~~~~~~
