Submission #248477

#	Time	Username	Problem	Language	Result	Execution time	Memory
248477		ernestvw	Horses (IOI15_horses)	C++11	17 / 100	1330 ms	53240 KiB

horses

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

const ll mod = 1e9 + 7;

int n;
vector<ll> C, P;
set<int> indices;

ll treeProd[4000000],treeMax[4000000];

void updateProd(int l, int r, int idx, int i, ll val) {
	if(idx < l || r < idx || r < l) return;
	if(l == r) {
		treeProd[i] = val;
		return;
	}
	updateProd(l, (l+r)/2, idx, 2*i+1, val);
	updateProd((l+r)/2+1, r, idx, 2*i+2, val);
	treeProd[i] = treeProd[2*i+1] * treeProd[2*i+2];
	treeProd[i] %= mod;
}

ll getProd(int l, int r, int L, int R, int i) {
	if(R < l || L > r || r < l) return 1;
	if(L <= l && r <= R) return treeProd[i];
	return (getProd(l, (l+r)/2, L, R, 2*i+1) * getProd((l+r)/2+1, r, L, R, 2*i+2)) % mod;
}

void updateMax(int l, int r, int idx, int i, ll val) {
	if(idx < l || r < idx || r < l) return;
	if(l == r) {
		treeMax[i] = val;
		return;
	}
	updateMax(l, (l+r)/2, idx, 2*i+1, val);
	updateMax((l+r)/2+1, r, idx, 2*i+2, val);
	treeMax[i] = max(treeMax[2*i+1], treeMax[2*i+2]);
}

ll getMax(int l, int r, int L, int R, int i) {
	if(R < l || L > r || r < l) return 0;
	if(L <= l && r <= R) return treeMax[i];
	return max(getMax(l, (l+r)/2, L, R, 2*i+1), getMax((l+r)/2+1, r, L, R, 2*i+2));
}

int solve() {
	ll prod = 1;
	int best = n-1, pbest = 1;
	int der = n;
	for(auto it = indices.rbegin(); it != indices.rend(); it++) {
		int i = *it;
		prod *= C[i];
		ll p = getMax(0, n-1, i, der-1, 0);
		if(prod > 1e9) break;
		if(prod * pbest <= C[i] * p) {
			best = i;
			prod = C[i];
			pbest = p;
		}
		der = i;
	}
	prod = getProd(0, n-1, 0, best, 0);
	prod *= pbest;
	prod %= mod;
	return int(prod);
}

int init(int N, int X[], int Y[]) {
	n = N;
	C.resize(n);
	P.resize(n);
	for(int i = 0; i < n; ++i) C[i] = X[i];
	for(int i = 0; i < n; ++i) P[i] = Y[i];
	memset(treeProd, 1, sizeof(P));
	memset(treeMax, 0, sizeof(P));
	for(int i = 0; i < n; ++i) {
		updateProd(0, n - 1, i, 0, C[i]);
		updateMax(0, n - 1, i, 0, P[i]);
	}

	for(int i = 0; i < n; ++i)
		if(C[i] > 1 || i == 0)
			indices.insert(i);

	return solve();
}

int updateX(int pos, int val) {
	updateProd(0, n-1, pos, 0, val);
	if(pos == 0 || val > 1) indices.insert(pos);
	C[pos] = val;
	return solve();
}

int updateY(int pos, int val) {
	updateMax(0, n-1, pos, 0, val);
	P[pos] = val;
	return solve();
}

Compilation message (stderr)

horses.cpp: In function 'int solve()':
horses.cpp:57:13: warning: conversion to 'double' from 'll {aka long long int}' may alter its value [-Wconversion]
   if(prod > 1e9) break;
             ^~~
horses.cpp:61:12: warning: conversion to 'int' from 'll {aka long long int}' may alter its value [-Wconversion]
    pbest = p;
            ^

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