Submission #237803

#	Time	Username	Problem	Language	Result	Execution time	Memory
237803		DS007	Building Bridges (CEOI17_building)	C++14	100 / 100	99 ms	65400 KiB

building

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

const int N = 1e5 + 5, H = 1e6 + 5;

class Line {
public:
    int m, c;

    Line() {
        m = 0;
        c = 1e18;
    }

    Line(int m_, int c_) {
        m = m_;
        c = c_;
    }

    int evaluate(int x) {
        return m * x + c;
    }
};

class LiChaoTree {
    Line *t;
    int n;

public:
    LiChaoTree(int n_) {
        n = n_;
        t = new Line[n * 4];
    }

    int insert(int v, int l, int r, Line nl) {
        if (l == r)
            return t[v] = nl.evaluate(l) < t[v].evaluate(l) ? nl : t[v], 1;

        int mid = (l + r) / 2;
        if (t[v].m > nl.m) swap(t[v], nl);
        if (t[v].evaluate(mid) > nl.evaluate(mid))
            swap(t[v], nl), insert(v * 2 + 1, mid + 1, r, nl);
        else
            insert(v * 2, l, mid, nl);
    }

    int query(int v, int l, int r, int x) {
        if (l == r)
            return t[v].evaluate(x);

        int mid = (l + r) / 2;
        if (x < mid)
            return min(t[v].evaluate(x), query(v * 2, l, mid, x));
        else
            return min(t[v].evaluate(x), query(v * 2 + 1, mid + 1, r, x));
    }
};

int h[N], w[N], dp[N];
int n, s;

int solveTestCase() {
    cin >> n;
    for (int i = 0; i < n; i++) cin >> h[i];
    for (int i = 0; i < n; i++) cin >> w[i], s += w[i];

    LiChaoTree lct(H);
    dp[0] = -w[0];
    lct.insert(1, 0, H, Line(-2 * h[0], dp[0] + h[0] * h[0]));

    for (int i = 1; i < n; i++)
        dp[i] = lct.query(1, 0, H, h[i]) + h[i] * h[i] - w[i], lct.insert(1, 0, H, Line(-2 * h[i], dp[i] + h[i] * h[i]));

    cout << dp[n - 1] + s;
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int test = 1;
    // cin >> test;
    while (test--)
        solveTestCase();
}

Compilation message (stderr)

building.cpp: In function 'long long int solveTestCase()':
building.cpp:76:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
building.cpp: In member function 'long long int LiChaoTree::insert(long long int, long long int, long long int, Line)':
building.cpp:46:5: warning: control reaches end of non-void function [-Wreturn-type]
     }
     ^

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