Submission #60116

#	Time	Username	Problem	Language	Result	Execution time	Memory
60116		dukati8	Horses (IOI15_horses)	C++14	54 / 100	1563 ms	104996 KiB

horses

#include "horses.h"
#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a; i<int(b); i++)
using namespace std;
int n;
long long x[500000],y[500000];
long long m=1000000000+7;
long long product;

pair<long long,long long> invgcd(long long a, long long b) {
	//Returns x and y such that ax+by=1
	if (a==1 && b==0) return make_pair(1,0);
	long long c=a%b;
	long long d=a/b;
	pair<long long, long long > ans = invgcd(b,c);
	return make_pair(ans.second,ans.first-ans.second*d);
}
long long inverse2(long long a) {
	pair<long long, long long > ans = invgcd(m,a);
	return ans.second+m;
}
long long powsmart(long long a,long long b) {
	if (b==1) return a;
  long long x=powsmart(a,b/2);
  x=(x*x)%m;
	if (b%2==0) {
		return x;
	}
	else
		return (a*x)%m;
}
long long inverse( long long a) {
	//calculate a**(m-2)
	return powsmart(a%m,m-2);

}
int init(int N, int X[], int Y[]) {
	n=N;
	rep (i,0,n) {
		x[i]=X[i];
		y[i]=Y[i];
	}
	product=1;
	rep (i,0,n) {
		product*=x[i];
		product%=m;
	}
	long long hi=y[n-1];
	long long divide=1;
	for (int i = n-2; i>=0; i--) {
		hi*=x[i+1];
		hi=max(hi,y[i]);
		divide*=x[i+1];
		if (hi>=1000000000) break;
	}
	long long ans=(hi%m)*product;
	ans%=m;
	ans*=inverse(divide);
	ans%=m;
	return ans;


}

int updateX(int pos, int val) {
	product*=inverse(x[pos]);
	product%=m;
	product*=val;
	product%=m;
	x[pos]=val;

	long long hi=y[n-1];
	long long divide=1;
	for (int i = n-2; i>=0; i--) {
		hi*=x[i+1];
		hi=max(hi,y[i]);
		divide*=x[i+1];
		if (hi>=1000000000) break;
	}
	long long ans=(hi%m)*product;
	ans%=m;
	ans*=inverse(divide);
	ans%=m;
	return ans;
}

int updateY(int pos, int val) {
	y[pos]=val;
	long long hi=y[n-1];
	long long divide=1;
	for (int i = n-2; i>=0; i--) {
		hi*=x[i+1];
		hi=max(hi,y[i]);
		divide*=x[i+1];
		if (hi>=1000000000) break;
	}
	long long ans=(hi%m)*product;
	ans%=m;
	ans*=inverse(divide);
	ans%=m;
	return ans;
}

Compilation message (stderr)

horses.cpp: In function 'long long int powsmart(long long int, long long int)':
horses.cpp:25:13: warning: declaration of 'x' shadows a global declaration [-Wshadow]
   long long x=powsmart(a,b/2);
             ^
horses.cpp:7:11: note: shadowed declaration is here
 long long x[500000],y[500000];
           ^
horses.cpp: In function 'int init(int, int*, int*)':
horses.cpp:61:9: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
  return ans;
         ^~~
horses.cpp: In function 'int updateX(int, int)':
horses.cpp:85:9: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
  return ans;
         ^~~
horses.cpp: In function 'int updateY(int, int)':
horses.cpp:102:9: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
  return ans;
         ^~~

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