Submission #1286534

#	Time	Username	Problem	Language	Result	Execution time	Memory
1286534		tschav_	Horses (IOI15_horses)	C++20	0 / 100	60 ms	15084 KiB

horses

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<ll> x, y;
int n;
int m;
ll prod = 1;
int idx = -1;
vector<int> st;
static const ll MOD = 1e9+7;

ll binpow(ll a, ll b, ll m) {
    a %= m;
    ll res = 1;
    while (b > 0) {
        if (b & 1)
            res = res * a % m;
        a = a * a % m;
        b >>= 1;
    }
    return res;
}

ll gety(int id){
	int lim = n;
	if(id < m-1) {
		lim = st[id+1];
	}
	ll mx = 0;
	for(int i = st[id]; i < lim; ++i){
		mx = max(mx, y[i]);
	}
	return mx;
}

ll solve() {
	ll mx = (idx == -1 ? 0 : gety(idx));
	ll curr = 1;
	for(int i = idx+1; i < m; ++i){
		curr *= x[st[i]];
		int G = gety(i);
		if(curr * G > mx) {
			mx = curr * G;
		}
	}
	return (mx%MOD * prod%MOD) % MOD;
}

void ind() {
	idx = -1;
	ll P = 1ll;
	for(int i = m-1; i >= 0; --i) {
		if(P * x[st[i]] > 1e9) {
			idx=i;
			break;
		} else P *= x[st[i]];
	}
}

void getprod() {
	prod = 1ll;
	for(int i = 0; i <= idx; ++i){
		prod = (prod * x[st[i]]) % MOD;
	}
}

int init(int N, int X[], int Y[]) {
	n = N;
	x.resize(n,0ll);
	y.resize(n,0ll);
	for(int i = 0; i < n; ++i) {
		x[i] = X[i];
		y[i] = Y[i];
		if(x[i] >= 2){
			st.push_back(i);
		}
	}
	m = st.size();

	ind();
	getprod();
	return int(solve());
}

int updateX(int pos, int val) {
	ll old = x[pos];
	x[pos] = val;

	if(val == 1 and old != 1) {
		st.erase(st.begin()+pos,st.begin()+pos+1);
	}
	if(val != 1 and old == 1) {
        st.insert(st.begin()+pos,pos);
	}
    int m = st.size();

	ind();
	if(pos <= idx) {
        prod = (prod * binpow(old, MOD-2,MOD)) % MOD;
        prod = (prod * val) % MOD;
	}
	return int(solve());
}

int updateY(int pos, int val) {
	y[pos] = val;
	ind();
	return int(solve());
}

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