| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 785427 | NothingXD | Horses (IOI15_horses) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef complex<ld> point;
typedef __uint128_t L;
struct FastMod {
ull b, m;
FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
ull reduce(ull a) {
ull q = (ull)((L(m) * a) >> 64);
ull r = a - q * b; // can be proven that 0 <= r < 2*b
return r >= b ? r - b : r;
}
};
FastMod FM(1e9+7);
void debug_out(){cerr << endl;}
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T){
cout << H << " ";
debug_out(T...);
}
#define debug(...) cerr << "(" << #__VA_ARGS__ << "): ", debug_out(__VA_ARGS__)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
const int maxn = 5e5 + 10;
const int mod = 1e9 + 7;
int n;
int x[maxn], y[maxn];
ll dp[maxn << 2][2];
bool of[maxn << 2];
int find(int v, int l, int r, int tmp){
if (!of[v] && 1ll * tmp * dp[v][1] < mod) return -1;
if (l + 1 == r) return l;
int mid = (l + r) >> 1;
int lc = v << 1;
int rc = lc | 1;
int res = find(rc, mid, r, tmp);
if (res == -1){
tmp *= dp[rc][1];
res = find(lc, l, mid, tmp);
}
return res;
}
void build2(int v, int l, int r){
if (l + 1 == r){
dp[v][0] = x[l] * y[l];
dp[v][1] = x[l];
return;
}
int mid = (l + r) >> 1;
int lc = v << 1;
int rc = lc | 1;
build2(lc, l, mid);
build2(rc, mid, r);
dp[v][0] = max(dp[lc][0], dp[lc][1] * dp[rc][0]);
dp[v][1] = dp[lc][1] * dp[rc][1];
if (dp[v][1] >= mod || of[lc] || of[rc]) of[v] = true;
dp[v][1] = FM.reduce(dp[v][1]);
}
void change2(int v, int l, int r, int idx){
if (l + 1 == r){
dp[v][0] = x[l] * y[l];
dp[v][1] = x[l];
return;
}
int mid = (l + r) >> 1;
int lc = v << 1;
int rc = lc | 1;
if (idx < mid) change2(lc, l, mid, idx);
else change2(rc, mid, r, idx);
dp[v][0] = max(dp[lc][0], dp[lc][1] * dp[rc][0]);
dp[v][1] = dp[lc][1] * dp[rc][1];
if (dp[v][1] >= mod || of[lc] || of[rc]) of[v] = true;
dp[v][1] = FM.reduce(dp[v][1]);
}
pll get2(int v, int l, int r, int ql, int qr){
if (ql <= l && r <= qr) return MP(dp[v][0], dp[v][1]);
int mid = (l + r) >> 1;
int lc = v << 1;
int rc = lc | 1;
pll a = {0, 1};
pll b = {0, 1};
if (qr > l && ql < mid) a = get2(lc, l, mid, ql, qr);
if (qr > mid && ql < r) b = get2(rc, mid, r, ql, qr);
return MP(max(a.F, a.S * b.F), FM.reduce(a.S * b.S));
}
int Calc(){
int idx = find(1, 0, n, 1);
if (idx == -1) idx = 0;
assert(idx < n-1);
int tmp = get2(1, 0, n, 0, idx+1).S;
ll tmp2 = FM.reduce(max(y[idx], get2(1, 0, n, idx+1, n).F));
return FM.reduce(1ll * tmp * tmp2);
}
int init(int N, int X[], int Y[]) {
n = N;
for (int i = 0; i < n; i++){
x[i] = X[i];
y[i] = Y[i];
}
build2(1, 0, n);
return Calc();
}
int updateX(int pos, int val) {
x[pos] = val;
change2(1, 0, n, pos);
return Calc();
}
int updateY(int pos, int val) {
y[pos] = val;
change2(1, 0, n, pos);
return Calc();
}