Submission #1171791

#	Time	Username	Problem	Language	Result	Execution time	Memory
1171791		julia_08	Fancy Fence (CEOI20_fancyfence)	C++20	25 / 100	11 ms	4164 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 - 1] - s[j]) % MOD;

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

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

    dp[i] = (aux + ((((h[i] * (h[i] + 1)) / 2) % MOD) * w[i]) % MOD) % MOD; // termina no i
    ans = (ans + dp[i] + (aux * (w[i] - 1)) % MOD + cnt) % MOD;

    q.push(i);

  }

  cout << ans << "\n";

  return 0;
}

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