Submission #380177

#	Time	Username	Problem	Language	Result	Execution time	Memory
380177		idk321	말 (IOI15_horses)	C++11	17 / 100	321 ms	16464 KiB

horses

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

using namespace std;
typedef long long ll;

const int mod = 1000000007;

const int N = 500000;
const int R = 710;

int n;
int* x;
int* y;


int best[R];
ll left1[R][R];
ll right1[R][R];





void spMod(ll& num)
{
    if (num >= mod)
    {
        num %= mod;
        num += mod;
    }
}

ll getBest()
{

    ll cbest = left1[0][best[0]] % mod;
    cbest *= y[best[0]];
    cbest %= mod;
    int ci = best[0];
    ll fac = 1;
    if (ci != min(R - 1, n - 1)) fac *= right1[0][ci + 1];
    spMod(fac);
    ll facAll = left1[0][ci];
    facAll %= mod;
    if (ci < R && ci < n) facAll *= right1[0][ci + 1];
    for (int a = R; a < n; a += R)
    {
        int i = best[a / R];



        fac *= left1[a / R][i % R];
        spMod(fac);
        facAll *= left1[a / R][i % R];
        facAll %= mod;


        if (fac * y[i] > y[ci])
        {
            cbest = facAll * y[i];
            cbest %= mod;
            ci = i;
            fac = 1;
        }

        if (i != min(n - 1, a + R - 1))
        {
            fac *= right1[a / R][(i + 1) % R];
            spMod(fac);
            facAll *= right1[a / R][(i + 1) % R];
            facAll %= mod;
        }
    }


    return cbest;
}


void makeBlock(int block)
{
    int ci = block * R;
    ll fac = 1;
    for (int i = block * R + 1; i < min(n, (block + 1) * R); i++)
    {
        fac *= x[i];
        spMod(fac);
        if (fac > y[ci] || fac * y[i] > y[ci])
        {
            ci = i;
            fac = 1;
        }
    }

    fac = 1;
    for (int i = 0; i <= ci; i++)
    {
        if (i + block * R >= n) continue;
        fac *= x[i + block * R];
        spMod(fac);
        left1[block][i] = fac;
    }
    left1[block][ci] = fac;

    fac = 1;
    for (int i = ci + 1; i + block * R < n && i < R; i++)
    {
        fac *= x[i + block * R];
        spMod(fac);
    }
    if (ci + 1 + block * R < n && ci + 1 < R) right1[block][ci + 1] = fac;

    best[block] = ci;
}

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

    for (int a = 0; a < R && a * R < n; a++)
    {
        makeBlock(a);
    }

    //cout << best[0] << endl;
    return getBest() % mod;
}

int updateX(int pos, int val) {

    x[pos] = val;

   makeBlock(pos / R);


    return getBest() % mod;
}

int updateY(int pos, int val) {

    y[pos] = val;

    makeBlock(pos / R);

    return getBest() % mod;
}

Compilation message (stderr)

horses.cpp: In function 'int init(int, int*, int*)':
horses.cpp:117:33: warning: declaration of 'N' shadows a global declaration [-Wshadow]
  117 | int init(int N, int X[], int Y[]) {
      |                                 ^
horses.cpp:9:11: note: shadowed declaration is here
    9 | const int N = 500000;
      |           ^
horses.cpp:128:22: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  128 |     return getBest() % mod;
      |            ~~~~~~~~~~^~~~~
horses.cpp: In function 'int updateX(int, int)':
horses.cpp:138:22: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  138 |     return getBest() % mod;
      |            ~~~~~~~~~~^~~~~
horses.cpp: In function 'int updateY(int, int)':
horses.cpp:147:22: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  147 |     return getBest() % mod;
      |            ~~~~~~~~~~^~~~~

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