Submission #86840

#	Time	Username	Problem	Language	Result	Execution time	Memory
86840		JustasZ	Horses (IOI15_horses)	C++14	17 / 100	1252 ms	48892 KiB

horses

#include "horses.h"
#include <bits/stdc++.h>
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) (int)a.size()
#define x first
#define y second
#define debug(...) "["<<#__VA_ARGS__<<": "<<__VA_ARGS__<<"]"
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int>pii;
const int maxn=5e5+100;
const int mod=1e9+7;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll pwr(ll a, ll pw)
{
    ll ret=1;
    while(pw>0)
    {
        if(pw&1)ret=ret*a%mod;
        a=a*a%mod;
        pw>>=1;
    }
    return ret;
}
ll modinv(ll a)
{
    return pwr(a, mod-2);
}
int N;
ll X[maxn], Y[maxn], seg[maxn*4];
set<int>pos;
void build(int id=1, int l=0, int r=N-1)
{
    if(l == r)
    {
        seg[id]=Y[l];
        return;
    }
    int mid=(l+r)/2;
    build(id*2, l, mid);
    build(id*2+1, mid+1, r);
    seg[id]=max(seg[id*2], seg[id*2+1]);
}
void modify(int p, ll d, int id=1, int l=0, int r=N-1)
{
    if(l == r)
    {
        seg[id]+=d;
        return;
    }
    int mid=(l+r)/2;
    if(p <= mid)modify(p, d, id*2, l, mid);
    else modify(p, d, id*2+1, mid+1, r);
    seg[id]=max(seg[id*2], seg[id*2+1]);
}
ll query(int x, int y, int id=1, int l=0, int r=N-1)
{
    if(l > y || r < x)return 0;
    if(l >= x && r <= y)return seg[id];
    int mid=(l+r)/2;
    return max(query(x, y, id*2, l, mid), query(x, y, id*2+1, mid+1, r));
}

ll F[maxn];
void upd(int p, ll val)
{
    for(; p<=N; p+=p&-p)
        F[p]=(F[p]*val)%mod;
}
ll get(int p)
{
    ll ret=1;
    for(; p>0; p-=p&-p)
        ret=(ret*F[p])%mod;
    return ret;
}
int getans()
{
    if(!sz(pos))return query(0, N-1)%mod;
    auto it=prev(pos.end());
    for(int c=0; c<=30; c++)
    {
        if(it == pos.begin())break;
        --it;
    }
    ll opt=*it, xbest=X[*it], xprod=1;
    bool big=false;
    while(it != pos.end())
    {
        xprod*=X[*it];
        if(xprod > mod)
        {
            big=true;
            xprod%=mod;
        }
        if(big && X[*it] >= 2)
        {
            opt=*it, xbest=xprod;
            ++it;
            continue;
        }
        assert(xprod < 1e18);
        assert(xprod % xbest == 0);
        if(xprod/xbest > (query(opt, N-1)+query(*it, N-1)-1)/query(*it, N-1))
            opt=*it, xbest=xprod;
        ++it;
    }
    return (int)(get(opt+1)*query(opt, N-1)%mod);
}
int init(int n, int x[], int y[])
{
    N=n;
    for(int i=0; i<N; i++)
        X[i]=x[i], Y[i]=y[i];
    for(int i=N-1; i>=0; i--)
        if(X[i] >= 2)
            pos.insert(i);
    build();
    for(int i=1; i<=N; i++)
        F[i]=1;
    for(int i=0; i<N; i++)
        upd(i+1, X[i]);
    return getans();
}
int updateX(int p, int val)
{
    upd(p+1, val*modinv(X[p])%mod);
    if(X[p] == 1 && val >= 2)pos.insert(p);
    if(X[p] >= 2 && val == 1)pos.erase(p);
    X[p]=val;
    return getans();
}
int updateY(int p, int val)
{
    ll d=val-Y[p];
    modify(p, d);
    Y[p]=val;
    return getans();
}
/*int main()
{
    ios_base::sync_with_stdio(false), cin.tie(0);
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    int n, A[maxn], B[maxn];
    cin>>n;
    for(int i=0; i<n; i++)
        cin>>A[i];
    for(int i=0; i<n; i++)
        cin>>B[i];
    cout<<init(n, A, B)<<"\n";
    int m;
    cin>>m;
    while(m--)
    {
        int a, b, c;
        cin>>a>>b>>c;
        if(a == 1)cout<<updateX(b, c)<<"\n";
        else cout<<updateY(b, c)<<"\n";
    }
    return 0;
}*/

Compilation message (stderr)

horses.cpp: In function 'int getans()':
horses.cpp:81:37: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
     if(!sz(pos))return query(0, N-1)%mod;
                        ~~~~~~~~~~~~~^~~~
In file included from /usr/include/c++/7/cassert:44:0,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:33,
                 from horses.cpp:2:
horses.cpp:104:24: warning: conversion to 'double' from 'll {aka long long int}' may alter its value [-Wconversion]
         assert(xprod < 1e18);
                        ^
horses.cpp:106:41: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
         if(xprod/xbest > (query(opt, N-1)+query(*it, N-1)-1)/query(*it, N-1))
                                         ^
horses.cpp:110:25: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
     return (int)(get(opt+1)*query(opt, N-1)%mod);
                      ~~~^~
horses.cpp:110:43: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
     return (int)(get(opt+1)*query(opt, N-1)%mod);
                                           ^

• Subtask 1: 17 / 17
• Subtask 2: 0 / 17
• Subtask 3: 0 / 20
• Subtask 4: 0 / 23
• Subtask 5: 0 / 23