Submission #303406

#	Time	Username	Problem	Language	Result	Execution time	Memory
303406		BeanZ	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	37 ms	5120 KiB

fancyfence

// I_Love_LPL
#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define endl '\n'
const int N = 1e5 + 5;
const int mod = 1e9 + 7;
ll h[N], w[N], sum[N], g[N];
ll dp[N];
int main(){
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        if (fopen("A.inp", "r")){
                freopen("test.inp", "r", stdin);
                freopen("test.out", "w", stdout);
        }
        ll n;
        cin >> n;
        ll ans = 0;
        for (int i = 1; i <= n; i++) cin >> h[i];
        for (int i = 1; i <= n; i++) cin >> w[i], g[i] = (g[i - 1] + w[i]) % mod;
        h[0] = 0;
        stack<ll> s;
        s.push(0);
        for (int i = 1; i <= n; i++){
                while (s.size()){
                        if (h[s.top()] > h[i]) s.pop();
                        else break;
                }
                dp[i] = (w[i] * (w[i] + 1) / 2) % mod * ((h[i] * (h[i] + 1) / 2) % mod) % mod;
                sum[i] = sum[s.top()] + (g[i - 1] - g[s.top()] + mod) % mod * ((h[i] * (h[i] + 1) / 2) % mod) % mod;
                dp[i] = (dp[i] + sum[i] * w[i]) % mod;
                ans = (ans + dp[i]) % mod;
                sum[i] = (sum[i] + ((h[i] * (h[i] + 1) / 2) % mod) * w[i] % mod) % mod;
                s.push(i);
        }
        cout << ans;
}
/*
2
2 2
2 4

3
1 3 2
2 2 2
*/

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:16:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   16 |                 freopen("test.inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:17:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   17 |                 freopen("test.out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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