Submission #919687

#	Time	Username	Problem	Language	Result	Execution time	Memory
919687		penguin133	Building Bridges (CEOI17_building)	C++17	100 / 100	40 ms	10576 KiB

building

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, H[100005], W[100005];
struct Line {
    mutable int k, m, p;
    bool operator<(const Line& o) const { return k < o.k; }
    bool operator<(int x) const { return p < x; }
};
struct LineContainer : multiset<Line, less<>> {
    // for doubles, use inf = 1/.0, div(a,b) = a / b
    static const int inf = 5e18;// implement this
    int div(int a, int b) { // floored division
        return a / b - ((a ^ b) < 0 && a % b);
    }
    bool isect(iterator x, iterator y) {
        if (y == end()) return x->p = inf, 0;
        if (x->k == y->k) x->p = x->m > y->m ? inf : -inf;
        else x->p = div(y->m - x->m, x->k - y->k);
        return x->p >= y->p;
    }
    void add(int k, int m) { // insert y = kx + m
        auto z = insert({k, m, 0}), y = z++, x = y;
        while (isect(y, z)) z = erase(z);
        if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
        while ((y = x) != begin() && (--x)->p >= y->p)
        isect(x, erase(y));
    }
    int query(int x) { // max query
        assert(!empty());
        auto l = *lower_bound(x);
        return l.k * x + l.m;
    }
};
int dp[100005], P[100005];

void solve(){
	cin >> n;
	for(int i = 1; i <= n; i++)cin >> H[i];
	for(int i = 1; i <= n; i++)cin >> W[i], P[i] = P[i - 1] + W[i];
	dp[1] = 0;
	LineContainer hull;
	hull.add(2 * H[1], -(H[1] * H[1] - P[1]));
	for(int i = 2; i <= n; i++){
		dp[i] = -hull.query(H[i]) + H[i] * H[i] + P[i - 1];
		hull.add(2 * H[i], -(H[i] * H[i] - P[i] + dp[i]));
	}
	cout << dp[n];
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

building.cpp:60:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   60 | main(){
      | ^~~~

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