Submission #285486

#	Time	Username	Problem	Language	Result	Execution time	Memory
285486		HynDuf	Mountains (IOI17_mountains)	C++14	0 / 100	1 ms	384 KiB

mountains

#include <bits/stdc++.h>
#include "mountains.h"
#define task "M"
#define all(v) (v).begin(), (v).end()
#define rep(i, l, r) for (int i = (l); i <= (r); ++i)
#define Rep(i, r, l) for (int i = (r); i >= (l); --i)
#define DB(X) { cerr << #X << " = " << (X) << '\n'; }
#define DB1(A, _) { cerr << #A << "[" << _ << "] = " << (A[_]) << '\n'; }
#define DB2(A, _, __) { cerr << #A << "[" << _ << "][" << __ << "] = " << (A[_][__]) << '\n'; }
#define DB3(A, _, __, ___) { cerr << #A << "[" << _ << "][" << __ << "][" << ___ << "] = " << (A[_][__][___]) << '\n'; }
#define PR(A, l, r) { cerr << '\n'; rep(_, l, r) DB1(A, _); cerr << '\n';}
#define SZ(x) ((int)(x).size())
#define pb push_back
#define eb emplace_back
#define pf push_front
#define F first
#define S second
#define by(x) [](const auto& a, const auto& b) { return a.x < b.x; } // sort(arr, arr + N, by(a));
#define next ___next
#define prev ___prev
#define y1 ___y1
#define left ___left
#define right ___right
#define y0 ___y0
#define div ___div
#define j0 ___j0
#define jn ___jn

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using namespace std;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vl;
const int N = 2003;
int dp[N][N];
bool can_reach(ii &A, ii &B, ii &C) // Line AC is not cut by B - A->B->C must go in counter clockwise order (A.x < B.x < C.x)
{
    return ((B.F - A.F) * (C.S - A.S) - (C.F - A.F) * (B.S - A.S)) >= 0;
}
int maximum_deevs(vi a)
{
    int n = SZ(a);
    vii aa;
    rep(i, 0, n - 1) aa.eb(i, a[i]);
    rep(r, 0, n - 1)
    {
        int lst = r, sum = 0; // the minimum index in [l, r] that lst can see r, .i.e. lst and r cannot be chose together
        dp[r][r] = 1;
        Rep(l, r - 1, 0)
        {
            dp[l][r] = dp[l][r - 1];
            if (can_reach(aa[l], aa[lst], aa[r]))
            {
                sum += dp[l + 1][lst - 1];
                lst = l;
            }
            dp[l][r] = max(dp[l][r], 1 + sum + dp[l][lst - 1]);
        }
    }
    return dp[0][n - 1];
}

//int main()
//{
//#ifdef HynDuf
//    freopen(task".in", "r", stdin);
//    //freopen(task".out", "w", stdout);
//#else
//    ios_base::sync_with_stdio(false); cin.tie(nullptr);
//#endif
//    int n;
//    vi a;
//    cin >> n;
//    rep(i, 1, n)
//    {
//        int x;
//        cin >> x;
//        a.eb(x);
//    }
//    cout << maximum_deevs(a);
//    return 0;
//}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 30
• Subtask 4: 0 / 30