Submission #615298

#	Time	Username	Problem	Language	Result	Execution time	Memory
615298		Do_you_copy	Holiday (IOI14_holiday)	C++17	100 / 100	314 ms	62856 KiB

holiday

//source: usaco.guide IOI2014 holiday
//only run to evaluate memory used#include <bits/stdc++.h>
#include <bits/stdc++.h>
#include "holiday.h"
#define MAXS 3100000
#define MAX 100005
#define SEG3LIM (1000000007)
using ll = long long;
///If I don't use packed here I will get MLE
struct  __attribute__((packed)) node {
    int left;
    int right;
    ll sum;
    int total;
};
///The idea is the following:
///I have a persistent seg3 that is able to do the folowing queries:
///What is the sum of the k biggest elements in the segment L-R (k,L nor R are constants)
///I need to answer those queries online
///After that I will use Divide And Conquer DP
///I will check which segment the guy will walk, how many visitations are left if he moves optimally
///(You can get his values with basic algebra) and TA-DA! Just use the function!
node memoria[MAXS];
int cur=1;
int alocar(void){
    return cur++;
}
int sz;
node nodes[MAX];
ll vals[MAX];
///Insert element in persistent seg3
void inserir(node* x,ll val,int p,int la=0,int ra=SEG3LIM-1){
    if(la==ra){
        assert(p==la);
        x->total++;
        x->sum+=val;
        return;
    }
    int m = (la+ra)/2;
    if(m>=p){
        auto old = x->left;
        x->left=alocar();
        memoria[x->left]=memoria[old];
        inserir(&memoria[x->left],val,p,la,m);
    }else {
        auto old = x->right;
        x->right=alocar();
        memoria[x->right]=memoria[old];
        inserir(&memoria[x->right],val,p,m+1,ra);
    }
    ll tot = 0,ss=0;
    if(x->left)tot+=memoria[x->left].sum;
    if(x->right)tot+=memoria[x->right].sum;
    if(x->left)ss+=memoria[x->left].total;
    if(x->right)ss+=memoria[x->right].total;
    x->sum=tot;
    x->total=ss;
}
///Query in persistent seg3
long long ans=0,limites,restante=0;
void walk(node* k,node* u,int la=0,int ra=SEG3LIM-1){
    if(!restante||!(k->sum))return;
    long long subsum=0,subtotal=0;
    subsum+=u->sum;
    subtotal+=u->total;
    if(k->total-subtotal<=restante){
        ans+=k->sum-subsum;
        restante-=k->total-subtotal;
        return;
    }
 
    int m=(la+ra)/2;
    int tem = 0;
    if(k->right){
        tem=memoria[k->right].total-memoria[u->right].total;
    }
    if(la==ra){
        ll pega = std::min(restante,k->total-subtotal);
        restante-=pega;
        ans+=((long long)la)*pega;
        return;
    }
    if(la==ra)return;
    walk(&memoria[k->right],&memoria[u->right],m+1,ra);
    walk(&memoria[k->left],&memoria[u->left],la,m);
}
node locais[MAX];
///Setting up the persistent seg3
void prepara(void){
    for(int i=0;i!=sz;++i){
        if(i)locais[i]=locais[i-1];
        ///I believe that you can compress the coordinates here to reduce memory
        ///Wasn't necessary tho
        inserir(&locais[i],vals[i],vals[i]);
    }
}
///Main cost query (I mentioned above how it works). Complexity O(log N). Maybe you can
///get AC with O(log^2 N), the time limit is very generous, I only used around 6% of it.
long long consulta(int l,int r,int p){
    ans=0;limites=1e7;restante=p;
    auto beta = &locais[r],alpha=&memoria[0];
    if(l){
        alpha=&locais[l-1];
    }
    walk(beta,alpha);
    return ans;
}
long long pode=0;
long long resp=0;
long long inicio=0;
///Here is our Divide and Conquer DP :)
void dp(int l,int r,int la,int ra){
    if(r<l)return;
    int m = (l+r)/2;
    ll ans = 0,split=inicio;
    for(int i=la;i<=ra;++i){
        ll dist1=(inicio-i),dist2=(m-inicio);
        ///Formula to get optimal cost to travel segment [i,m] while starting in the beginning
        ll custo = (std::min(dist1,dist2)*2)+std::max(dist1,dist2);
        ll tem = pode-custo;
        if(tem<=0)continue;
        ll bonus = consulta(i,m,tem);
        if(bonus>ans){
            ans=bonus;
            split=i;
        }
    }
    resp=std::max(resp,ans);
    dp(l,m-1,la,split);
    dp(m+1,r,split,ra);
}
///Main function
long long int findMaxAttraction(int n, int start, int d, int attraction[]) {
    sz=n;
    for(int i=0;i!=n;++i){
        vals[i]=attraction[i];
    }
    inicio=start;
    pode=d;
    prepara();
    dp(inicio,n-1,0,inicio);
    return resp;
}

Compilation message (stderr)

holiday.cpp: In function 'void walk(node*, node*, int, int)':
holiday.cpp:73:9: warning: variable 'tem' set but not used [-Wunused-but-set-variable]
   73 |     int tem = 0;
      |         ^~~

• Subtask 1: 7 / 7
• Subtask 2: 23 / 23
• Subtask 3: 17 / 17
• Subtask 4: 53 / 53