Submission #537804

#	Time	Username	Problem	Language	Result	Execution time	Memory
537804		maomao90	Planine (COCI21_planine)	C++17	110 / 110	527 ms	56288 KiB

Main

// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;

template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define MT make_tuple
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

#define INF 1000000005
#define LINF 1000000000000000005ll
#define MAXN 1000005

int n, h;
int x[MAXN], y[MAXN];
int ans;

struct frac {
    ll a, b;
    frac(): a(0), b(1) {}
    frac(ll _a): a(_a), b(1) {}
    frac(ll _a, ll _b): a(_a), b(_b) {
        if (b == 0) {
            a = LINF;
            b = 1;
            return;
        }
        ll g = __gcd(abs(a), abs(b));
        a /= g;
        b /= g;
        if (b < 0) {
            a *= -1;
            b *= -1;
        }
    }
    frac operator+(const frac &o) const {
        return frac(a * o.b + b * o.a, b * o.b);
    }
    frac operator-(const frac &o) const {
        return *this + (-o);
    }
    frac operator-() const {
        return frac(-a, b);
    }
    bool operator<(const frac &o) const {
        assert(b > 0 && o.b > 0);
        return a * o.b < b * o.a;
    }
    bool operator>(const frac &o) const {
        assert(b > 0 && o.b > 0);
        return a * o.b > b * o.a;
    }
    bool operator==(const frac &o) const {
        return a == o.a && b == o.b;
    }
    bool operator<=(const frac &o) const {
        return *this == o || *this < o;
    }
    friend ostream& operator<<(ostream &os, const frac &o) {
        return os << o.a << '/' << o.b;
    }
};

struct Range {
    frac l, r;
    bool operator<(const Range &o) const {
        return r < o.r;
    }
};

frac l[MAXN], r[MAXN];
vector<Range> ranges;

int main() {
#ifndef DEBUG
    ios::sync_with_stdio(0), cin.tie(0);
#endif
    cin >> n >> h;
    REP (i, 0, n) {
        cin >> x[i] >> y[i];
    }
    REP (zz, 0, 2) {
        vi pts;
        REP (i, 1, n - 1) {
            auto ori = [&] (int a, int b, int c) {
                // b - a cross c - a
                ll x1 = x[b] - x[a], y1 = y[b] - y[a],
                x2 = x[c] - x[a], y2 = y[c] - y[a];
                return x1 * y2 - x2 * y1;
            };
            while (pts.size() >= 2 && ori(pts[pts.size() - 2], pts[pts.size() - 1], i) > 0) {
                pts.pop_back();
            }
            if (i % 2 == 0) {
                int j = pts.back();
                l[i] = frac(x[i]) - frac((ll) (x[i] - x[j]) * (h - y[i]), y[j] - y[i]);
            }
            pts.pb(i);
        }
        swap(l, r);
        REP (i, 0, n) {
            x[i] *= -1;
        }
        reverse(x, x + n);
        reverse(y, y + n);
    }
    REP (i, 0, n) {
        r[i] = -r[i];
    }
    reverse(r, r + n);
    for (int i = 2; i < n - 1; i += 2) {
        cerr << i << ": " << l[i] << ' ' << r[i] << '\n';
        ranges.pb((Range) {l[i], r[i]});
    }
    sort(ALL(ranges));
    frac x = frac(-1e12);
    REP (i, 0, ranges.size()) {
        if (x < ranges[i].l) {
            x = ranges[i].r;
            ans++;
        }
    }
    cout << ans << '\n';
    return 0;
}


/*
2: -6/1 2/3
4: -1/1 5/1
6: 2/1 8/1
*/

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:13:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Range>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 | #define REP(i, s, e) for (int i = s; i < e; i++)
......
  141 |     REP (i, 0, ranges.size()) {
      |          ~~~~~~~~~~~~~~~~~~~            
Main.cpp:141:5: note: in expansion of macro 'REP'
  141 |     REP (i, 0, ranges.size()) {
      |     ^~~

• Subtask 1: 20 / 20
• Subtask 2: 30 / 30
• Subtask 3: 60 / 60