Submission #984240

#	Time	Username	Problem	Language	Result	Execution time	Memory
984240		LucaIlie	Horses (IOI15_horses)	C++17	34 / 100	1567 ms	45652 KiB

horses

#include "horses.h"
#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 5e5;
const int MOD = 1e9 + 7;

struct AIB1 {
    int aib[MAX_N + 1];

    void init() {
        for ( int i = 0; i <= MAX_N; i++ )
            aib[i] = 1;
    }

    void update( int i, int x ) {
        while ( i <= MAX_N ) {
            aib[i] = (long long)aib[i] * x % MOD;
            i += (i & -i);
        }
    }

    int query( int i ) {
        int p = 1;
        while ( i > 0 ) {
            p = (long long)p * aib[i] % MOD;
            i -= (i & -i);
        }
        return p;
    }
} horses;

struct AIB2 {
    double aib[MAX_N + 1];


    void init() {
        for ( int i = 0; i <= MAX_N; i++ )
            aib[i] = 0;
    }

    void update( int i, double x ) {
        while ( i <= MAX_N ) {
            aib[i] += x;
            i += (i & -i);
        }
    }

    double query( int i ) {
        double p = 0;
        while ( i > 0 ) {
            p += aib[i];
            i -= (i & -i);
        }
        return p;
    }
} cost;

int lgPut( int a, int n ) {
    if ( n == 0 )
        return 1;

    int p = lgPut( a, n / 2 );
    p = (long long)p * p % MOD;
    if ( n % 2 == 1 )
        p = (long long)p * a % MOD;

    return p;
}

int inv( int x ) {
    return lgPut( x, MOD - 2 );
}

int n;
int x[MAX_N + 1], y[MAX_N + 1];
set<pair<double, int>> s;


void calc() {
    s.clear();
    horses.init();
    cost.init();
    for ( int i = 1; i <= n; i++ ) {
        horses.update( i, x[i] );
        cost.update( i, log( x[i] ) );
        s.insert( { cost.query( i ) + log( y[i] ), i } );
    }
}

int answer() {
    calc();
    int i = s.rbegin()->second;
    return (long long)horses.query( i ) * y[i] % MOD;
}

int init( int N, int X[], int Y[] ) {
    n = N;

    for ( int i = n - 1; i >= 0; i-- )
        x[i + 1] = X[i], y[i + 1] = Y[i];

    horses.init();
    cost.init();
    for ( int i = 1; i <= n; i++ ) {
        horses.update( i, x[i] );
        cost.update( i, log( x[i] ) );
        s.insert( { cost.query( i ) + log( y[i] ), i } );
    }

    return answer();
}

int updateX( int pos, int val ) {
    int i = pos + 1;

    s.erase( { cost.query( i ) + log( y[i] ), i } );
    cost.update( i, -log( x[i] ) );
    horses.update( i, inv( x[i] ) );

    x[i] = val;

    cost.update( i, log( x[i] ) );
    horses.update( i, x[i] );
    s.insert( { cost.query( i ) + log( y[i] ), i } );

    return answer();
}

int updateY( int pos, int val ) {
    int i = pos + 1;

    s.erase( { cost.query( i ) + log( y[i] ), i } );
    y[i] = val;
    s.insert( { cost.query( i ) + log( y[i] ), i } );

    return answer();
}

Compilation message (stderr)

horses.cpp: In member function 'void AIB1::update(int, int)':
horses.cpp:19:44: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   19 |             aib[i] = (long long)aib[i] * x % MOD;
      |                      ~~~~~~~~~~~~~~~~~~~~~~^~~~~
horses.cpp: In member function 'int AIB1::query(int)':
horses.cpp:27:39: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   27 |             p = (long long)p * aib[i] % MOD;
      |                 ~~~~~~~~~~~~~~~~~~~~~~^~~~~
horses.cpp: In function 'int lgPut(int, int)':
horses.cpp:65:26: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   65 |     p = (long long)p * p % MOD;
      |         ~~~~~~~~~~~~~~~~~^~~~~
horses.cpp:67:30: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   67 |         p = (long long)p * a % MOD;
      |             ~~~~~~~~~~~~~~~~~^~~~~
horses.cpp: In function 'int answer()':
horses.cpp:95:48: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   95 |     return (long long)horses.query( i ) * y[i] % MOD;
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~

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