Submission #1171777

#	Time	Username	Problem	Language	Result	Execution time	Memory
1171777		julia_08	Fancy Fence (CEOI20_fancyfence)	C++20	0 / 100	1 ms	328 KiB

fancyfence

#include <bits/stdc++.h>
#define int long long

using namespace std;

const int MAXN = 1e5 + 10;
const int MOD = 1e9 + 7;

int h[MAXN], w[MAXN], s[MAXN];

int dp[MAXN];

int32_t main(){
  cin.tie(0)->sync_with_stdio(0);

  int n; cin >> n;

  for(int i=1; i<=n; i++){
    cin >> h[i];
  }

  for(int i=1; i<=n; i++){
    cin >> w[i];
    s[i] = s[i - 1] + w[i];
  }

  stack<int> q;

  int ans = 0;

  for(int i=1; i<=n; i++){

    while(!q.empty() && h[q.top()] > h[i]) q.pop();

    int j = 0;

    if(!q.empty()) j = q.top();

    int l = s[i] - s[j];

    dp[i] = ((dp[j] + ((h[i] * (h[i] + 1)) / 2) % MOD) * l) % MOD;

    int cnt = (((((h[i] * (h[i] + 1)) / 2) % MOD) * ((w[i] * (w[i] + 1)) / 2) % MOD) % MOD +
              (((h[i] * (h[i] + 1)) / 2) % MOD) * ((w[i] * (s[i - 1] - s[j])) % MOD)) % MOD;

    ans = (ans + dp[j] * w[i] + cnt) % MOD;

    q.push(i);

  }

  cout << ans << "\n";

  return 0;
}

• Subtask 1: 0 / 0
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27