Submission #997426

#	Time	Username	Problem	Language	Result	Execution time	Memory
997426		Neco_arc	Building Bridges (CEOI17_building)	C++17	100 / 100	90 ms	10696 KiB

building

#include <bits/stdc++.h>
//#include <bits/debug.hpp>

#define ll long long
#define all(x) x.begin(), x.end()
#define Neco "xay cau"
#define resp(x) sort(all(x)), x.resize(unique(all(x)) - x.begin())
#define getbit(x,i) ((x >> i)&1)
#define _left id * 2, l, mid
#define _right id * 2 + 1, mid + 1, r
#define cntbit(x) __builtin_popcountll(x)
#define fi(i, a, b) for(int i = a; i <= b; i++)
#define fid(i, a, b) for(int i = a; i >= b; i--)
#define maxn (int) 2e5 + 7

using namespace std;

const ll mod = 1e9 + 7; //972663749
const ll base = 911382323;

int n;
ll h[maxn], s[maxn];
ll dp[maxn];

struct CHT {
    vector<pair<ll, ll>> P;
    vector<long double> X;

    void init() { P.clear(), X.clear(); }
    bool empty() { return P.empty(); }

    long double inter(pair<ll, ll> x, pair<ll, ll> y) {
        return 1. * (y.second - x.second) / (x.first - y.first);
    }

    void Add(pair<ll, ll> p) {
        long double Nw = -1e18;
        while(!P.empty()) {
            assert(P.back().first <= p.first);
            if(P.back().first == p.first && P.back().second >= p.second) return;

            Nw = inter(p, P.back());
            if(Nw < X.back()) P.pop_back(), X.pop_back();
            else break;
        }

        P.push_back(p), X.push_back(Nw);
    }

    ll get(ll x) {
        if(P.empty()) return -1e18;
        int it = upper_bound(all(X), x) - X.begin() - 1;
        return P[it].first * x + P[it].second;
    }
} Cht[18];

void Add(pair<ll, ll> p) {
    vector<pair<ll, ll>> P = {p};
    fi(i, 0, 17) {
        if(Cht[i].empty()) {
            sort(all(P), greater<pair<ll, ll>>());
            for(auto [x, y] : P) Cht[i].Add({-x, -y});

            break;
        }
        else {
            for(auto [x, y] : Cht[i].P) P.push_back({-x, -y});
            Cht[i].init();
        }
    }
}

ll get(ll x, ll ans = 1e18) {
    fi(i, 0, 17) ans = min(ans, -Cht[i].get(x));
    return ans;
}

void solve()
{

    cin >> n;
    fi(i, 1, n) cin >> h[i];
    fi(i, 1, n) {
        ll x; cin >> x;
        s[i] = s[i - 1] + x;
    }

    Add({ -2 * h[1], h[1] * h[1] - s[1] + dp[1] });
    fi(i, 2, n) {
        dp[i] = get(h[i]) + s[i - 1] + h[i] * h[i];
        Add({ -2 * h[i], h[i] * h[i] - s[i] + dp[i] });
    }

    cout << dp[n];
}


int main()
{

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    if(fopen(Neco".inp", "r")) {
        freopen(Neco".inp", "r", stdin);
        freopen(Neco".out", "w", stdout);
    }


    int nTest = 1;
//    cin >> nTest;


    while(nTest--)
    {
        solve();
    }


    return 0;
}

Compilation message (stderr)

building.cpp: In function 'int main()':
building.cpp:106:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |         freopen(Neco".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
building.cpp:107:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |         freopen(Neco".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40