Submission #683617

#	Time	Username	Problem	Language	Result	Execution time	Memory
683617		sysia	Fancy Fence (CEOI20_fancyfence)	C++17	0 / 100	2 ms	492 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;

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

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

int power(int a, int b){
    if (!b) return 1LL;
    int k = power(a, b/2);
    k = mul(k, k);
    if (b&1) k = mul(k, a);
    return k;
}

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

    FAU(int n){
        sz = n+1;
        for (int i = 0; i<sz; i++){
            rep.emplace_back(i);
            mn.emplace_back(i);
            mx.emplace_back(i);
        }
    }

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

    T find(int a){
        a = f(a);
        return {mn[a], mx[a]};
    }

    bool u(int a, int b){
        a = f(a); b = f(b);
        if (a == b) return 0;
        mn[a] = min(mn[a], mn[b]);
        mx[a] = max(mx[a], mx[b]);
        rep[b] = a;
        return 1;
    }
};

int pairs(int x){
    return x*(x-1)/2;
}

void solve(){
    int n; cin >> n;
    vector<int>h(n+1), w(n+1);
    for (int i = 1; i<=n; i++) cin >> h[i];
    vector<int>l(n+1), r(n+1);
    int sum = 1;
    for (int i = 1; i<=n; i++) {
        l[i] = sum;
        cin >> w[i];
        sum += w[i];
        r[i] = sum-1;
    }
    vector<int>s = h;
    sort(s.begin(), s.end());
    s.erase(unique(s.begin(), s.end()), s.end());
    auto get = [&](int x){return lower_bound(s.begin(), s.end(), x) - s.begin();};
    vector<vector<int>>sweep(n+1);
    for (int i = 1; i<=n; i++){
        sweep[get(h[i])].emplace_back(i);
    }
    vector<int>used(n+1);
    FAU dsu(n+1);
    int ans = 0;
    for (int i = n; i>=1; i--){
        for (auto idx: sweep[i]){
            int height = h[idx];
            if (idx > 1 && used[idx-1]) dsu.u(idx-1, idx);
            if (idx < n && used[idx+1]) dsu.u(idx, idx+1);
            used[idx] = 1;
            auto [mn, mx] = dsu.find(idx);
            debug(mn, mx, height, mul(height, power(2, r[mx]-l[mn]+1)-1));
            add(ans, mul(height, power(2, pairs(r[mx]-l[mn]+1))));
        }
    }
    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: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27