Submission #725025

#	Time	Username	Problem	Language	Result	Execution time	Memory
725025		grogu	Žarulje (COI15_zarulje)	C++14	100 / 100	929 ms	26084 KiB

zarulje

#define here cerr<<"===========================================\n"
#define dbg(x) cerr<<#x<<": "<<x<<endl;
#include <bits/stdc++.h>
#define ld double
#define ll long long
#define ull unsigned long long
#define llinf 100000000000000000LL // 10^17
#define iinf 2000000000 // 2*10^9
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define all(a) a.begin(),a.end()
using namespace std;

#define mod 1000000007
#define maxn 200005
ll fact[maxn];
ll add(ll x,ll y){
    x+=y;
    if(x<0){
        x%=mod;
        x+=mod;
    }else{
        if(x>=mod) x%=mod;
    }
    return x;
}
ll mul(ll a,ll b){
	ll ans = (a*b)%mod;
	if(ans<0) ans+=mod;
	return ans;
}
ll po(ll x,ll y){
    if(y==0) return 1LL;
    ll ans = po(x,y/2);
    ans = mul(ans,ans);
    if(y&1) ans = mul(ans,x);
    return ans;
}
ll inv(ll x){return po(x,mod-2);}
ll ch(ll n,ll k){
    if(k>n) return 0;
    ll ans = fact[n];
    ans = mul(ans,inv(fact[k]));
    ans = mul(ans,inv(fact[n-k]));
    return ans;
}
ll n,k;
ll a[maxn];
ll ask[maxn];
ll rez[maxn];
ll cntl[maxn],cntr[maxn];
vector<pll> v[maxn];
void tc(){
	ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
    fact[0] = 1;
    for(ll i = 1;i<maxn;i++) fact[i] = mul(fact[i-1],i);
    cin >> n >> k;
    for(ll i = 1;i<=n;i++) cin >> a[i];
    ll ans = 1;
    stack<ll> st;
    for(ll i = n;i>=1;i--){
        while(st.size()&&st.top()>a[i]){
            cntr[st.top()]--;
            v[i].pb({st.top(),1});
            st.pop();
        }
        cntr[a[i]]++;
        v[i].pb({a[i],-1});
        st.push(a[i]);
    }
    while(st.size()) st.pop();
    for(ll i = 1;i<=n;i++){
        for(pll p : v[i]){
            ll x = p.fi;
            ll d = p.sc;
            ans = mul(ans,inv(ch(cntr[x]+cntl[x],cntl[x])));
            cntr[x]+=d;
            ans = mul(ans,ch(cntr[x]+cntl[x],cntl[x]));
        }
        rez[i] = ans;
        while(st.size()&&st.top()>a[i]){
            ll x = st.top();
            ans = mul(ans,inv(ch(cntr[x]+cntl[x],cntl[x])));
            cntl[x]--;
            ans = mul(ans,ch(cntr[x]+cntl[x],cntl[x]));
            st.pop();
        }
        ll x = a[i];
        ans = mul(ans,inv(ch(cntr[x]+cntl[x],cntl[x])));
        cntl[x]++;
        ans = mul(ans,ch(cntr[x]+cntl[x],cntl[x]));
        st.push(a[i]);
    }
    for(ll i = 1;i<=k;i++){
        ll x; cin >> x;
        cout<<rez[x]<<endl;
    }
}

int main(){
	ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
	int t; t = 1;
	while(t--){
		tc();
	}
	return 0;
}
/**
5 2
3 5 1 4 3
3 5
**/

• Subtask 1: 22 / 22
• Subtask 2: 38 / 38
• Subtask 3: 40 / 40