Submission #336943

#	Time	Username	Problem	Language	Result	Execution time	Memory
336943		blue	Horses (IOI15_horses)	C++11	0 / 100	561 ms	524292 KiB

horses

#include "horses.h"
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
#include <set>
using namespace std;


long long mod = 1e9 + 7;

class segtree
{
public:
    int l;
    int r;
    long long mx;
    long long p;

    segtree* left = NULL;
    segtree* right = NULL;

    segtree()
    {
        ;
    }

    segtree(int L, int R)
    {
        l = L;
        r = R;
        mx = p = 0;
        if(l == r) return;
        int m = (l+r)/2;
        left = new segtree(l, m);
        right = new segtree(m+1, r);
    }

    long long rangemax(int L, int R)
    {
        if(R < l || r < L) return 0;
        if(L <= l && r <= R) return mx;
        return max(left->rangemax(L, R), right->rangemax(L, R));
    }

    long long rangeprod(int L, int R)
    {
        if(R < l || r < L) return 1;
        if(L <= l && r <= R) return p;
        return (left->rangeprod(L, R) * right->rangeprod(L, R)) % mod;
    }

    void update(int I, long long V)
    {
        if(I < l || r < I) return;
        if(l == r) mx = p = V;
        else
        {
            left->update(I, V);
            right->update(I, V);
            mx = max(left->mx, right->mx);
            p = (left->p * right->p) % mod;
        }
    }
};

struct growth
{
    int i;
    int x;
};

bool operator < (growth A, growth B)
{
    return A.i > B.i;
}

int N;
segtree X;
segtree Y;
set<growth> Xset;

int compute()
{
    long long fullprod = 1;
    int fullprod_pos = 0;
    for(growth g: Xset)
    {
        if(fullprod * g.x >= 1e9) break;
        fullprod *= g.x;
        fullprod_pos = g.i;
    } //fullprod_pos is the leftmost position such that Xprod(fullprod_pos, N-1) < 1e9
      //The leftmost selling point is fullprod_pos - 1

    long long res = 1;
    int res_pos = 0;

    for(growth g: Xset)
    {
        if(g.i < fullprod_pos - 1) break;
        if(X.rangeprod(fullprod_pos - 1, g.i) * Y.rangemax(g.i, N-1) > res)
        {
            res = X.rangeprod(fullprod_pos - 1, g.i) * Y.rangemax(g.i, N-1);
            res_pos = g.i;
        }
    }
    return int( (X.rangeprod(0, res_pos) * Y.rangemax(res_pos, N-1)) % mod );
}

int init(int n, int x[], int y[])
{
    N = n;
    X = segtree(-1, N-1);
    Y = segtree(-1, N-1);

    for(int i = 0; i < N; i++)
    {
        X.update(i, x[i]);
        Y.update(i, y[i]);

        if(x[i] != 1) Xset.insert(growth{i, x[i]});
    }

    return compute();
}

int updateX(int pos, int val)
{
    X.update(pos, val);
    Xset.erase(growth{pos, val});
    if(val != 1) Xset.insert(growth{pos, val});

    return compute();
}

int updateY(int pos, int val)
{
    Y.update(pos, val);
    return compute();
}

Compilation message (stderr)

horses.cpp: In function 'int compute()':
horses.cpp:89:21: warning: conversion from 'long long int' to 'double' may change value [-Wconversion]
   89 |         if(fullprod * g.x >= 1e9) break;
      |            ~~~~~~~~~^~~~~

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