Submission #707038

#	Time	Username	Problem	Language	Result	Execution time	Memory
707038		marvinthang	Horses (IOI15_horses)	C++17	100 / 100	578 ms	51352 KiB

horses

/*************************************
*    author: marvinthang             *
*    created: 08.03.2023 15:25:43    *
*************************************/

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

using namespace std;

#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)

template <class T> T invGeneral(T a, T b) {
    a %= b;
    if (!a) return b == 1 ? 0 : -1;
    T x = invGeneral(b, a);
    return x == -1 ? -1 : ((1 - 1LL * b * x) / a + b) % b;
}

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

int N, X[MAX], Y[MAX], bit[MAX], st[MAX << 2];
set <int, greater <int>> pos;

void build(int i, int l, int r) {
	if (r - l == 1) {
		st[i] = Y[l];
		return;
	}
	int m = l + r >> 1;
	build(i << 1, l, m);
	build(i << 1 | 1, m, r);
	st[i] = max(st[i << 1], st[i << 1 | 1]);
}

void update(int i, int l, int r, int p) {
	if (r - l == 1) {
		st[i] = Y[l];
		return;
	}
	int m = l + r >> 1;
	if (p < m) update(i << 1, l, m, p);
	else update(i << 1 | 1, m, r, p);
	st[i] = max(st[i << 1], st[i << 1 | 1]);
}

int getMax(int i, int l, int r, int u, int v) {
	if (l >= v || r <= u) return 0;
	if (u <= l && r <= v) return st[i];
	int m = l + r >> 1;
	return max(getMax(i << 1, l, m, u, v), getMax(i << 1 | 1, m, r, u, v));
}

void update(int i, int v) {
	for (++i; i <= N; i += i & -i) bit[i] = 1LL * bit[i] * v % MOD;
}

int getMul(int i) {
	int res = 1;
	for (++i; i > 0; i &= i - 1) res = 1LL * res * bit[i] % MOD;
	return res;
}

int solve(void) {
	int res = -1;
	long long cb = 1;
	int r = N, ma = 0, mb = 0;
	for (int l: pos) {
		int ca = getMax(1, 0, N, l, r);
		if (1LL * ca * mb >= 1LL * ma * cb) {
			res = 1LL * getMul(l) * ca % MOD;
			ma = ca; mb = cb;
		}
		cb *= X[l];
		if (cb > MOD) break;
		r = l;
	}
	return res;
}

int init(int n, int x[], int y[]) {
	N = n;
	fill(bit, bit + N + 1, 1);
	REP(i, N) {
		X[i] = x[i]; Y[i] = y[i];
		if (!i || X[i] != 1) {
			update(i, X[i]);
			pos.insert(i);
		}
	}
	build(1, 0, N);
	return solve();
}

int updateX(int i, int val) {	
	if (X[i] != 1) {
		update(i, invGeneral(X[i], MOD));
		pos.erase(i);
	}
	X[i] = val;
	if (!i || X[i] != 1) {
		update(i, X[i]);
		pos.insert(i);
	}
	return solve();
}

int updateY(int i, int val) {
	Y[i] = val;
	update(1, 0, N, i);
	return solve();
}

Compilation message (stderr)

horses.cpp: In function 'void build(int, int, int)':
horses.cpp:31:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   31 |  int m = l + r >> 1;
      |          ~~^~~
horses.cpp: In function 'void update(int, int, int, int)':
horses.cpp:42:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   42 |  int m = l + r >> 1;
      |          ~~^~~
horses.cpp: In function 'int getMax(int, int, int, int, int)':
horses.cpp:51:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   51 |  int m = l + r >> 1;
      |          ~~^~~
horses.cpp: In function 'void update(int, int)':
horses.cpp:56:59: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   56 |  for (++i; i <= N; i += i & -i) bit[i] = 1LL * bit[i] * v % MOD;
      |                                          ~~~~~~~~~~~~~~~~~^~~~~
horses.cpp: In function 'int getMul(int)':
horses.cpp:61:56: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   61 |  for (++i; i > 0; i &= i - 1) res = 1LL * res * bit[i] % MOD;
      |                                     ~~~~~~~~~~~~~~~~~~~^~~~~
horses.cpp: In function 'int solve()':
horses.cpp:72:31: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   72 |    res = 1LL * getMul(l) * ca % MOD;
      |          ~~~~~~~~~~~~~~~~~~~~~^~~~~
horses.cpp:73:18: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   73 |    ma = ca; mb = cb;
      |                  ^~
horses.cpp: In instantiation of 'T invGeneral(T, T) [with T = int]':
horses.cpp:98:33:   required from here
horses.cpp:17:20: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   17 |     return x == -1 ? -1 : ((1 - 1LL * b * x) / a + b) % b;
      |            ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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