Submission #1111311

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111311		luvna	Building Bridges (CEOI17_building)	C++14	100 / 100	45 ms	25672 KiB

building

#include<bits/stdc++.h>

#define all(v) v.begin(), v.end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define endl "\n"

using namespace std;

typedef long long ll;

const int N = 1e6 + 15;

int n, k;
int a[N];
vector<int> compress;

struct line {
    ll a, b;

    line() : a(0), b(0) {}
    line (ll a, ll b) : a(a), b(b) {}

    ll calc (ll x) { return a * x + b; }

    ll slope() { return a; }
};

struct liChao {
    vector<line> tr;

    liChao() {}
    liChao (int sz) : tr(sz + 1, line(0, LLONG_MAX)) {}

    void update (line f, int l, int r) {
        if (l > r) return;
        int mid = (l + r) >> 1;
        if (l == r) {
            tr[mid] = (f.calc(l) < tr[mid].calc(l) ? f : tr[mid]);
            return;
        }
        if (f.calc(mid) < tr[mid].calc(mid)) swap(tr[mid], f);
        if (f.slope() > tr[mid].slope())
            update(f, l, mid - 1);
        if (f.slope() < tr[mid].slope())
            update(f, mid + 1, r);
    }

    ll query (int p, int l, int r) {
        int mid = (l + r) >> 1;
        ll cur = tr[mid].calc(p);
        if (p == mid) return cur;
        if (p < mid) return min(query(p, l, mid - 1), cur);
        if (p > mid) return min(query(p, mid + 1, r), cur);
    }
};

ll dp[N];
ll pref[N];

void solve(){
    cin >> n;

    for(int i = 1; i <= n; i++) cin >> a[i];
    for(int i = 1; i <= n; i++) cin >> pref[i], pref[i] += pref[i-1];

    liChao solver(N);

    solver.update(line(-2LL*a[1], 1LL*a[1]*a[1] - pref[1]),0,N);

    for(int i = 2; i <= n; i++){
        dp[i] = 1LL*a[i]*a[i] + pref[i-1] + solver.query(a[i],0,N);
        solver.update(line(-2LL*a[i], 1LL*a[i]*a[i] + dp[i] - pref[i]),0,N);
    }

    cout << dp[n];
}

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

    #define task "task"

    if(fopen(task".INP", "r")){
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }

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

Compilation message (stderr)

building.cpp: In member function 'll liChao::query(int, int, int)':
building.cpp:54:5: warning: control reaches end of non-void function [-Wreturn-type]
   54 |     }
      |     ^
building.cpp: In function 'int main()':
building.cpp:85:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
building.cpp:86:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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