Submission #1013592

#	Time	Username	Problem	Language	Result	Execution time	Memory
1013592		daffuwu	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	27 ms	5456 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
#define fr first
#define sc second
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

long long n, h[100069], w, dp[100069], ans, ps[100069];
const long long dv = 1e9+7;
stack<long long> stk;

long long calc(long long a, long long b)
{
    if (a%2 == 0) a/=2;
    else b/=2;
    return a%dv*(b%dv)%dv;
}

int main() 
{
    long long i, j;
    scanf("%lld", &n);
    for (i=1; i<=n; i++)
    {
        scanf("%lld", h+i);
    }
    stk.push(0);
    for (i=1; i<=n; i++)
    {
        scanf("%lld", &w);
        ps[i] = ps[i-1]+w;
        for (; h[i]<=h[stk.top()]; stk.pop());
        j = stk.top();
        ans += (calc(ps[i]-ps[j], ps[i]-ps[j]+1)-calc(ps[i-1]-ps[j], ps[i-1]-ps[j]+1))*calc(h[i], h[i]+1)%dv;
        ans += dp[j]*w%dv;
        ans %= dv;
        dp[i] = (dp[j]+calc(h[i], h[i]+1)*((ps[i]-ps[j])%dv)%dv)%dv;
        stk.push(i);
    }
    if (ans<0) ans += dv;
    printf("%lld\n", ans);
}

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |     scanf("%lld", &n);
      |     ~~~~~^~~~~~~~~~~~
fancyfence.cpp:24:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |         scanf("%lld", h+i);
      |         ~~~~~^~~~~~~~~~~~~
fancyfence.cpp:29:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         scanf("%lld", &w);
      |         ~~~~~^~~~~~~~~~~~

• 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