Submission #746768

#	Time	Username	Problem	Language	Result	Execution time	Memory
746768		bgnbvnbv	Event Hopping (BOI22_events)	C++14	100 / 100	176 ms	28784 KiB

events

#include<bits/stdc++.h>
#define TASKNAME "codeforce"
#define pb push_back
#define pli pair<int,int>
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;
using ll=long long;
const ll maxN=1e5+10;
const ll inf=1e18;
const ll mod=1e9+7;
struct node
{
    ll val,id;
    node()
    {
        val=inf,id=inf;
    }
    node operator+(const node&o)
    {
        node ans;
        if(val<o.val) ans.val=val,ans.id=id;
        else ans=o;
        return ans;
    }
}st[4*maxN];
ll n,q;
void update(ll pos,ll val,ll id=1,ll l=1,ll r=n)
{
    if(l==r)
    {
        st[id].val=val;
        st[id].id=l;
        return;
    }
    ll mid=l+r>>1;
    if(pos<=mid) update(pos,val,id*2,l,mid);
    else update(pos,val,id*2+1,mid+1,r);
    st[id]=st[id*2]+st[id*2+1];
}
node get(ll i,ll j,ll id=1,ll l=1,ll r=n)
{
    if(j<l||r<i) return node();
    if(i<=l&&r<=j) return st[id];
    ll mid=l+r>>1;
    return get(i,j,id*2,l,mid)+get(i,j,id*2+1,mid+1,r);
}
struct qq
{
    ll s,e,id;
    bool operator<(const qq&o)
    {
        if(e==o.e) return s<o.s;
        return e<o.e;
    }
}a[maxN];
ll pos[maxN];
ll pre[maxN][19];
void solve()
{
   cin >> n >> q;
   for(int i=1;i<=n;i++)
   {
        cin >> a[i].s >> a[i].e;
        a[i].id=i;
   }
   sort(a+1,a+n+1);
   for(int i=1;i<=n;i++)
   {
       pos[a[i].id]=i;
       ll low=1,high=i-1;
       while(low<=high)
       {
           ll mid=low+high>>1;
           if(a[mid].e<a[i].s) low=mid+1;
           else high=mid-1;
       }
       auto val=get(low,i-1);
       if(val.val==inf||val.val>=a[i].s) pre[i][0]=i;
       else pre[i][0]=val.id;
       update(i,a[i].s);
   }
   for(int j=1;j<=18;j++)
   {
       for(int i=1;i<=n;i++)
       {
           pre[i][j]=pre[pre[i][j-1]][j-1];
       }
   }
   for(int i=1;i<=q;i++)
   {
        ll x,y;
        cin >> x >> y;
        x=pos[x];
        y=pos[y];
        if(x==y)
        {
            cout << 0<<'\n';
        }
        else if(a[x].e==a[y].e)
        {
            cout << 1<<'\n';
        }
        else if(x>y)
        {
            cout << "impossible\n";
        }
        else if(a[x].e<=a[y].e&&a[x].e>=a[y].s)
        {
            cout << 1 << '\n';
        }
        else
        {
            ll ans=0;
            for(int j=18;j>=0;j--)
            {
                if(a[pre[y][j]].s>a[x].e)
                {
                    y=pre[y][j],ans+=1<<j;
                }
            }
            if(a[pre[y][0]].s<=a[x].e&&a[pre[y][0]].e>=a[x].e)
            {
                ans+=2;
                cout << ans << '\n';
            }
            else
            {
                cout << "impossible\n";
            }
        }
   }
}
int main()
{
    fastio
    //freopen(TASKNAME".INP","r",stdin);
    //freopen(TASKNAME".OUT","w",stdout);
    solve();
}

Compilation message (stderr)

events.cpp: In function 'void update(ll, ll, ll, ll, ll)':
events.cpp:37:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   37 |     ll mid=l+r>>1;
      |            ~^~
events.cpp: In function 'node get(ll, ll, ll, ll, ll)':
events.cpp:46:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   46 |     ll mid=l+r>>1;
      |            ~^~
events.cpp: In function 'void solve()':
events.cpp:75:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   75 |            ll mid=low+high>>1;
      |                   ~~~^~~~~

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