Submission #1124364

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124364		Whisper	Fancy Fence (CEOI20_fancyfence)	C++20	100 / 100	35 ms	5704 KiB

fancyfence

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX                     100005
struct info{
    int w, h, id;
    info(){}
    info(int _w, int _h, int _id): w(_w), h(_h), id(_id){}

    bool operator < (const info& o) const{
        return h > o.h;
    }
} A[MAX];

int power(int a, int exp){
    int res = 1;
    for (; exp > 0; exp >>= 1, a = (a * a) % Mod) if(exp & 1){
        res = (res * a) % Mod;
    }
    return res;
}
const int inv4 = power(4, Mod - 2);

int pa[MAX], siz[MAX], nArr, vis[MAX];

int fp(int u){
    return u == pa[u] ? u : pa[u] = fp(pa[u]);
}
int ans = 0;
int mul(int a, int b){
    return 1LL * a * b % Mod;
}

int ask(int w, int h){
    return mul(mul(mul(w, w + 1), mul(h, h + 1)), inv4);
}

void add(int &x, int y){
    x += y;
    if(x >= Mod) x %= Mod;
    while(x < 0) x += Mod;
}
bool joint (int u, int v, int h){
    u = fp(u), v = fp(v);
    if (u == v) return false;

    add(ans, -ask(siz[u], h));
    add(ans, -ask(siz[v], h));
    add(ans, ask(siz[u] + siz[v], h));
    add(siz[u], siz[v]);
    pa[v] = u;
    return true;
}

void process(void){
    cin >> nArr;
    for (int i = 1; i <= nArr; ++i) cin >> A[i].h;
    for (int i = 1; i <= nArr; ++i) cin >> A[i].w;
    for (int i = 1; i <= nArr; ++i){
        A[i].id = i;
        pa[i] = i, siz[i] = A[i].w;
    }

    sort(A + 1, A + nArr + 1);
    for (int i = 1; i <= nArr; ++i){
        int h = A[i].h, id = A[i].id;
        ans += ask(A[i].w, A[i].h);
        if(vis[id + 1]) joint(id, id + 1, h);
        if(vis[id - 1]) joint(id, id - 1, h);

        vis[id] = true;
    }

    cout << ans;
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    // freopen(name".inp", "r", stdin);
    // freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

• 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