Submission #825384

#	Time	Username	Problem	Language	Result	Execution time	Memory
825384		grogu	Chorus (JOI23_chorus)	C++14	40 / 100	38 ms	4460 KiB

chorus

#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 eb emplace_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()
#define ceri(a,l,r) {cerr<<#a<<": ";for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
#define cer(a) {cerr<<#a<<": ";for(ll x_ : a) cerr<<x_<< " ";cerr<<endl;}
#define si(a) (ll)(a.size())
using namespace std;


#define maxn 5005
ll n,k;
ll a[maxn];
ll c[maxn];
ll ps[maxn];
ll sz = 0;
ll dp[maxn][maxn];
struct line{
    ll n,k;
    line(){n = llinf;k = 0;}
    line(ll n_,ll k_){n = n_,k = k_;}
    ll operator()(ll x){
        return k*x+n;
    }
};
line t[2*maxn];
ll ls[2*maxn],rs[2*maxn],tsz = 0,root = 0;
void init(ll &v,ll tl,ll tr){
    if(!v) v = ++tsz;
    t[v] = line();
    if(tl==tr) return;
    ll mid = (tl+tr)/2;
    init(ls[v],tl,mid);
    init(rs[v],mid+1,tr);
}
void upd(ll v,ll tl,ll tr,line f){
    line g = t[v];
    if(tl==tr){
        if(f(tl)<g(tl)) t[v] = f;
        return;
    }
    ll mid = (tl+tr)/2;
    if(f(tl)>g(tl)) swap(f,g);
    if(f(mid)<=g(mid)){t[v] = f;upd(rs[v],mid+1,tr,g);}
    else{t[v] = g;upd(ls[v],tl,mid,f);}
}
ll get(ll v,ll tl,ll tr,ll i){
    if(tl==tr) return t[v](i);
    ll mid = (tl+tr)/2;
    if(i<=mid) return min(get(ls[v],tl,mid,i),t[v](i));
    return min(get(rs[v],mid+1,tr,i),t[v](i));
}
int main(){
	ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
    cin >> n >> k;
    string s; cin >> s;
    for(ll i = 1;i<=2*n;i++){
        if(s[i-1]=='A') a[i] = 1;
    }
    ll b = 0;
    for(ll i = 2*n;i>=1;i--){
        if(a[i]==1){
            c[++sz] = b;
        }else b++;
    }
    for(ll i = 1;i<=n;i++) ps[i] = ps[i-1] + c[i];
    dp[0][0] = 0;
    for(ll i = 1;i<=n;i++) dp[i][0] = dp[0][i] = llinf;
    ll e = 0;
    for(ll j = 1;j<=k;j++){
        multiset<ll> s;
        init(root,1,n);
        e = 1;
        s.insert(dp[0][j-1]);
        for(ll i = 1;i<=n;i++){
            while(e<=i&&c[e]<=i){
                s.erase(s.find(dp[e-1][j-1]));
                line f(ps[e-1]+dp[e-1][j-1],-e);
                upd(root,1,n,f);
                e++;
            }
            dp[i][j] = llinf;
            if(si(s)) dp[i][j] = *s.begin();
            dp[i][j] = min(dp[i][j],get(root,1,n,i) - ps[e-1] + e*i);
            s.insert(dp[i][j-1]);
        }
    }
    //for(ll i = 0;i<=n;i++) ceri(dp[i],0,k);
    cout<<dp[n][k]<<endl;
	return (0-0);
}
/**
5 2
AABABABBAB

**/

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 0 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13