Submission #1175757

#	Time	Username	Problem	Language	Result	Execution time	Memory
1175757		InvMOD	Fancy Fence (CEOI20_fancyfence)	C++20	0 / 100	0 ms	328 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define gcd __gcd
#define sz(v) (int) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define REV(i, a, b) for(int i = (a); i >= (b); i--)
#define dbg(x) "[" #x " = " << (x) << "]"
///#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}

const int N = 2e5+5;
const ll MOD = 1e9+7;
const ll INF = 1e18;


int add(int x, int y){
    return (x + y < MOD ? x + y : x + y - MOD);
}

int sub(int x, int y){
    return add(x - y, MOD);
}

int mul(int x, int y){
    return (1ll * x * y) % MOD;
}

void solve()
{
    int n; cin >> n;

    vector<int> h(n + 1), w(n + 1);
    FOR(i, 1, n) cin >> h[i];
    FOR(i, 1, n) cin >> w[i];

    vector<int> pw(n + 1);
    FOR(i, 1, n) pw[i] = add(w[i], pw[i - 1]);

    vector<int> ph(n + 1);
    FOR(i, 1, n) ph[i] = add(h[i], ph[i - 1]);

    vector<int> dp(n + 1);

    stack<int> st; st.push(0);

    FOR(i, 1, n){
        while(h[i] <= h[st.top()]) st.pop();

        dp[i] = add(dp[st.top()], mul(sub(pw[i], pw[st.top()]), h[i]));
        st.push(i);
    }

    int answer = 0;
    FOR(i, 1, n) answer = add(answer, dp[i]);

    while(sz(st) > 1) st.pop();
    FOR(i, 1, n){
        while(w[i] <= w[st.top()]) st.pop();

        dp[i] = add(dp[st.top()], mul(sub(ph[i], ph[st.top()]), w[i]));
        st.push(i);
    }

    FOR(i, 1, n) answer = add(answer, dp[i]);

    cout << answer << "\n";
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP","r",stdin);
        freopen(name".OUT","w",stdout);
    }

    int t = 1; //cin >> t;
    while(t--) solve();
    return 0;
}

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:91:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |         freopen(name".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• 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