Submission #907520

#	Time	Username	Problem	Language	Result	Execution time	Memory
907520		sysia	Fancy Fence (CEOI20_fancyfence)	C++17	12 / 100	1 ms	348 KiB

fancyfence

//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;

void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << "'" << x << "'";}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 1e9+7;
const int I = (mod+1)/2;

int mul(int a, int b){
    return (a*b)%mod;
}

int C2(int x){
    return mul(x, mul(x-1, I));
}

void add(int &a, int b){
    a += b;
    if (a >= mod) a-=mod;
}

struct DSU{
    vector<int>rep, mn, mx, sz;

    DSU(int n){
        rep.resize(n+1);
        iota(rep.begin(), rep.end(), 0);
        mx = rep; mn = rep;
        sz.assign(n+1, 1);
    }

    T get(int x){
        x = f(x);
        return {mn[x], mx[x]};
    }

    int f(int a){
        return a == rep[a] ? a : rep[a] = f(rep[a]);
    }

    bool u(int a, int b){
        a = f(a);b = f(b);
        if (a == b) return false;
        if (sz[a] < sz[b]) swap(a, b);
        sz[a] += sz[b];
        mn[a] = min(mn[a], mn[b]);
        mx[a] = max(mx[a], mx[b]);
        rep[b] = a;
        return true;
    }
};


void solve(){
    int n; cin >> n;
    vector<int>h(n+1), w(n+1), pref(n+1);
    vector<T>s;
    for (int i = 1; i<=n; i++) {
        cin >> h[i];
        s.emplace_back(h[i], i);
    }
    DSU dsu(n+2);
    for (int i = 1; i<=n; i++) {
        cin >> w[i];
        pref[i] = pref[i-1] + w[i];
    }
    sort(s.rbegin(), s.rend());
    int ans = 0;
    vector<bool>vis(n+1);
    for (auto [h, i]: s){
        int tmp = C2(w[i]+1);
        if (i + 1 <= n && vis[i+1]) dsu.u(i, i+1);
        if (i - 1 >= 1 && vis[i-1]) dsu.u(i, i-1);
        vis[i] = 1;
        auto [L, R] = dsu.get(i);
        add(tmp, mul(w[i], pref[R]-pref[L-1]-w[i]));
        add(tmp, mul(pref[i-1]-pref[L-1], pref[R]-pref[i]));
        add(ans, mul(C2(h+1), tmp));
    }
    cout << ans << "\n";
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

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

    return 0;
}

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