#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mod = 1e9 + 7;
struct mint {
int v;
mint() {
v = 0;
}
mint(ll x) {
if (x >= mod) {
v = x % mod;
} else {
v = x;
}
}
mint& operator+=(const mint &b) {
if ((v += b.v) >= mod) {
v -= mod;
}
return *this;
}
friend mint operator+(mint a, mint b) {
return a += b;
}
mint& operator-=(const mint &b) {
if ((v -= b.v) < 0) {
v += mod;
}
return *this;
}
friend mint operator-(mint a, mint b) {
return a -= b;
}
mint& operator*=(const mint &b) {
v = 1ll * v * b.v % mod;
return *this;
}
friend mint operator*(mint a, mint b) {
return a *= b;
}
mint power(mint a, int b) {
mint ans = 1;
while (b) {
if (b & 1) {
ans *= a;
}
a *= a, b >>= 1;
}
return ans;
}
mint& operator/=(const mint &b) {
v = 1ll * v * power(b, mod - 2).v % mod;
return *this;
}
friend mint operator/(mint a, mint b) {
return a /= b;
}
friend ostream& operator<<(ostream &os, mint a) {
return os << a.v;
}
friend istream& operator>>(istream &is, mint &a) {
return is >> a.v;
}
};
const int N = 100'005;
mint prf[N];
int main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int n;
cin >> n;
int h[n + 1], w[n];
for (int i = 0; i < n; i++) {
cin >> h[i];
}
for (int i = 0; i < n; i++) {
cin >> w[i];
}
for (int i = 0; i < n; i++) {
prf[i + 1] = prf[i] + w[i];
}
h[n] = -2e9;
stack<int> s;
s.push(n);
mint ans = 0, sum = 0;
for (int l = n - 1; l >= 0; l--) {
while (h[l] <= h[s.top()]) {
int st = s.top();
s.pop();
int en = s.top();
sum -= (prf[en] - prf[st]) * h[st];
sum -= (prf[en] - prf[st]) * (h[st] * h[st]);
sum += (prf[en] - prf[st]) * h[l];
sum += (prf[en] - prf[st]) * h[l] * h[l];
}
ans += (mint(w[l]) * (w[l] + 1) / 2) * (mint(h[l]) * (h[l] + 1) / 2);
ans += sum * w[l] / mint(2);
s.push(l);
sum += mint(h[l]) * w[l];
sum += mint(h[l]) * h[l] * w[l];
}
cout << ans << '\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
604 KB |
Output is correct |
2 |
Incorrect |
1 ms |
604 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
604 KB |
Output is correct |
2 |
Correct |
0 ms |
604 KB |
Output is correct |
3 |
Correct |
1 ms |
604 KB |
Output is correct |
4 |
Correct |
1 ms |
604 KB |
Output is correct |
5 |
Correct |
0 ms |
604 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
856 KB |
Output is correct |
2 |
Correct |
1 ms |
600 KB |
Output is correct |
3 |
Correct |
29 ms |
1116 KB |
Output is correct |
4 |
Correct |
57 ms |
2768 KB |
Output is correct |
5 |
Correct |
59 ms |
2772 KB |
Output is correct |
6 |
Correct |
57 ms |
2652 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
1 ms |
604 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
604 KB |
Output is correct |
2 |
Incorrect |
1 ms |
604 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
600 KB |
Output is correct |
2 |
Incorrect |
1 ms |
600 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
604 KB |
Output is correct |
2 |
Incorrect |
1 ms |
604 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |