#include <bits/stdc++.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)
{
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;
}
Compilation message
/tmp/cc0Qq3Ci.o: In function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/cc1fM6T4.o:mountains.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
