Submission #515051

#	Time	Username	Problem	Language	Result	Execution time	Memory
515051		Killer2501	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	47 ms	6724 KiB

fancyfence

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define pb push_back
#define pll pair<ll, ll>
#define pii pair<int, int>
#define fi first
#define se second
using namespace std;
const int N = 2e5+5;
const int M = 26;
const ll inf = 1e15;
const ll mod = 1e9+7;
const ld ex = 1e-9;
int n, t, k, m, d[N], lab[N];
ll ans, tong, a[N], b[N], c[N], l[N], r[N], cnt;
string s;
struct node
{
    int x, y, val;
    int vx, vy;
    node(){}
    node(int _x, int _vx, int _y, int _vy)
    {
        x = _x;
        vx = _vx;
        y = _y;
        vy = _vy;
    }
};
ll pw(ll k, ll n)
{
    ll total = 1;
    for(; n; n >>= 1)
    {
        if(n&1)total = total * k % mod;
        k = k * k % mod;
    }
    return total;
}
ll C(ll u, ll v)
{
    if(u > v)return 0;
    return a[v] * b[u] % mod * b[v-u] % mod;
}
void add(ll& x, ll y)
{
    x += y;
    if(x >= mod)x -= mod;
}
vector<int> vi;
void sol()
{
    cin >> n;
    for(int i = 1; i <= n; i ++)cin >> a[i];
    for(int i = 1; i <= n; i ++)
    {
        cin >> c[i];
        b[i] = b[i-1] + c[i];
    }
    for(int i = 1; i <= n; i ++)
    {
        while(!vi.empty() && a[vi.back()] > a[i])vi.pop_back();
        l[i] = vi.empty() ? 0 : vi.back();
        vi.pb(i);
    }
    vi.clear();
    for(int i = n; i > 0; i --)
    {
        while(!vi.empty() && a[vi.back()] >= a[i])vi.pop_back();
        r[i] = vi.empty() ? n+1 : vi.back();
        vi.pb(i);
    }
    for(int i = 1; i <= n; i ++)
    {
        tong = ((b[r[i]-1]-b[i])%mod*((b[i]-b[l[i]])%mod)%mod+c[i]*(c[i]+1)/2%mod+(b[i-1]-b[l[i]])%mod*c[i]%mod) % mod;
        cnt = a[i] * (a[i]+1) % mod * pw(2, mod-2) % mod;
        //cout << cnt <<" ";
        ans = (ans + cnt * tong  % mod) % mod;
        //cout << cnt <<" "<<tong << '\n';
    }
    cout << ans;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
    #define task "test"
    if(fopen(task".inp", "r"))
	{
		freopen(task".inp", "r", stdin);
		freopen(task".out", "w", stdout);
    }
    int ntest = 1;
    //cin >> ntest;
    while(ntest -- > 0)
    sol();
}
/*

*/

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:93:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |   freopen(task".inp", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:94:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |   freopen(task".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