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답안 #902602

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
902602 2024-01-10T19:57:45 Z joelgun14 Building Bridges (CEOI17_building) C++17
100 / 100
 107 ms 13048 KB 
// header file
#include <bits/stdc++.h>
// pragma
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
// macros
#define endl "\n"
#define ll long long
#define mp make_pair
#define ins insert
#define lb lower_bound
#define pb push_back
#define ub upper_bound
#define lll __int128
#define fi first
#define se second
using namespace std;
ll sqr(ll a) {
    return a * a;
}
const ll is_query = -(1LL<<62);
struct line {
    ll m, b;
    mutable function<const line*()> succ;
    bool operator<(const line &rhs) const {
        if(rhs.b != is_query) 
            return m < rhs.m;
        const line* s = succ();
        if(!s)
            return 0;
        ll x = rhs.m;
        return b - s -> b < (s -> m - m) * x;
    }
};
struct dynamic_hull : public multiset<line> {
    const ll inf = LLONG_MAX;
    bool bad(iterator y) {
        auto z = next(y);
        // basically if the line is the same
        // if the line is the same then we will pick the lower line
        if(y == begin()) {
            if(z == end()) return 0;
            return y -> m == z -> m && y -> b <= z -> b;
        }
        auto x = prev(y);
        if(z == end()) {
            return y -> m == x -> m && y -> b <= x -> b;
        }
        // v1 is with prev
        ll v1 = (x -> b - y -> b);
        // check in case slope is same
        if(y -> m == x -> m) 
            v1 = x -> b > y -> b ? inf : -inf;
        else
            v1 /= (y -> m - x -> m);
        // v2 is with next
        ll v2 = (y -> b - z -> b);
        if(z -> m == y -> m)
            v2 = y -> b > z -> b ? inf : -inf;
        else
            v2 /= (z -> m - y -> m);
        return v1 >= v2;
    }
    void insert_line(ll m, ll b) {
        auto y = insert({m, b});
        y -> succ = [=] {return next (y) == end() ? 0 : &*next(y); };
        if(bad(y)) {
            erase(y);
            return;
        }
        while(next(y) != end() && bad(next(y)))
            erase(next(y));
        while(y != begin() && bad(prev(y)))
            erase(prev(y));
    }
    ll eval(ll x) {
        auto l = *lower_bound((line) {x, is_query});
        return l.m * x + l.b;
    }
};
dynamic_hull cht;
int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n;
    cin >> n;
    int h[n], w[n];
    for(int i = 0; i < n; ++i)
        cin >> h[i];
    for(int i = 0; i < n; ++i)
        cin >> w[i];
    // we choose first and we choose last
    // the problem is we need to choose some number of pillars
    // the factors of choosing a pillar
    // height
    // cost of removing the pillar
    // use dynamic cht dp opt
    ll dp[n], pref[n];
    memset(dp, 0, sizeof(dp));
    pref[0] = 0;
    for(int i = 1; i < n; ++i)
        pref[i] = pref[i - 1] + w[i];
    cht.insert_line(2 * h[0], -sqr(h[0]));
    for(int i = 1; i < n; ++i) {
        dp[i] = -cht.eval(h[i]) + pref[i - 1] + sqr(h[i]);
        cht.insert_line(2 * h[i], -(dp[i] + sqr(h[i]) - pref[i]));
    }
    cout << dp[n - 1] << endl;
    return 0;
}

Subtask #1
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 1 ms 344 KB Output is correct
5 Correct 1 ms 600 KB Output is correct

Subtask #2
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 74 ms 3924 KB Output is correct
2 Correct 54 ms 3868 KB Output is correct
3 Correct 52 ms 3840 KB Output is correct
4 Correct 46 ms 3744 KB Output is correct
5 Correct 58 ms 5492 KB Output is correct

Subtask #3
40.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 1 ms 344 KB Output is correct
5 Correct 1 ms 600 KB Output is correct
6 Correct 74 ms 3924 KB Output is correct
7 Correct 54 ms 3868 KB Output is correct
8 Correct 52 ms 3840 KB Output is correct
9 Correct 46 ms 3744 KB Output is correct
10 Correct 58 ms 5492 KB Output is correct
11 Correct 47 ms 3780 KB Output is correct
12 Correct 66 ms 3868 KB Output is correct
13 Correct 33 ms 3676 KB Output is correct
14 Correct 57 ms 4040 KB Output is correct
15 Correct 107 ms 13048 KB Output is correct
16 Correct 68 ms 5480 KB Output is correct
17 Correct 23 ms 3860 KB Output is correct
18 Correct 20 ms 3784 KB Output is correct