Submission #245306

#	Time	Username	Problem	Language	Result	Execution time	Memory
245306		LittleFlowers__	The Big Prize (IOI17_prize)	C++17	20 / 100	110 ms	5448 KiB

prize

#include <bits/stdc++.h>
using namespace std;
#define in ({int x=0;int c=getchar(),n=0;for(;!isdigit(c);c=getchar()) n=(c=='-');for(;isdigit(c);c=getchar()) x=x*10+c-'0';n?-x:x;})
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//mt19937 rng(1012);
int rnd(int l,int r){return l+rng()%(r-l+1);}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0);
#define forinc(a,b,c) for(int a=b,_c=c;a<=_c;++a)
#define fordec(a,b,c) for(int a=b,_c=c;a>=_c;--a)
#define forv(a,b) for(auto&a:b)
#define fi first
#define se second
#define pb push_back
#define ii pair<int,int>
#define mt make_tuple
#define all(a) a.begin(),a.end()
#define reset(f, x) memset(f, x, sizeof(f))
#define gg exit(0);

#ifndef UNX
#include "prize.h"
#endif // UNX

const int N=200010;

int n,asked;
vector<int> dd[N];

#ifdef UNX
int arr[N];
vector<int> ask(int p){
    asked++;
    int x=0, y=0;
    forinc(i,1,p)   x+=arr[i]<arr[p+1];
    forinc(i,p+2,n) y+=arr[i]<arr[p+1];
    return {x,y};
}
#endif // UNX

vector<int> qry(int i){
    return dd[i].size() ? dd[i] : dd[i]=ask(i-1);
}

int same(int i,int j){
    auto x=qry(i), y=qry(j);
    return x[0]+x[1]==y[0]+y[1];
}
int cnt(int i,int j){
    if(i>j)  swap(i,j);
    auto x=qry(i), y=qry(j);
    return y[0]-x[0];
}

int solve(int l){
    int i=l, sz=0;
    while(i<n){
        fordec(j,log2(n-i+1),0){
            int t=i+(1<<j);
            if(t>n) continue;
            if(same(l,t) && cnt(l,t)==sz) i=t;
        }
        if(i==n) break;
        auto a=qry(++i);
        if(a[0]+a[1]==0) return i-1;
        sz++;
    }
    i=l; int piv=sz;
    while(i>1){
        fordec(j,log2(i),0){
            int t=i-(1<<j);
            if(t<1) continue;
            if(same(l,t) && cnt(l,t)==sz-piv) i=t;
        }
        if(i==1) break;
        auto a=qry(--i);
        if(a[0]+a[1]==0) return i-1;
        sz++;
    }
    auto a=qry(l);
    //if(a[0]+a[1]+sz!=n) exit(-1);
    return -1;
}

int find_best(int nn){
    auto a=qry(1); n=nn;
    if(a[0]+a[1]==0) return 0;
    if(a[0]+a[1]==1){
        int le=0,mi,ri=n-1;
        while(le<=ri){
            mi=(le+ri)/2;
            a=qry(mi+1);
            if(a[0]+a[1]==0) return mi;
            if(a[0]) ri=mi-1; else le=mi+1;
        }
    }
    int x,tmp=-1;
    forinc(t,1,10){
        int i=rnd(1,n);
        auto a=qry(i);
        if(tmp<a[0]+a[1]){
            tmp=a[0]+a[1];
            x=i;
        }
    }
    if((n-tmp)+(n-tmp)<n) exit(-1);
    return solve(x);
}

#ifdef UNX
main(){
    #define task "TASK"
    if(fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        //freopen(task".out","w",stdout);
    }

    n=in;
    forinc(i,1,n) arr[i]=in;

    cout<<find_best(n)<<"\n";
    cerr<<asked;


}
#endif // UNX

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:106:19: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return solve(x);
                   ^

• Subtask 1: 20 / 20
• Subtask 2: 0 / 80