#779271 (D) No.2012 Largest Triangle

• 問題: No.2012 Largest Triangle
• ユーザー: hos.lyric
• 提出日時: 2022-07-16 22:36:23
• 言語: D (dmd 2.112.0)
• 結果: AC
• 実行時間: 186 ms / 2,500 ms
• コード長: 3,063 bytes
• コンパイル時間: 1,158 ms
• コンパイル使用メモリ: 127,864 KB
• 実行使用メモリ: 19,308 KB
• 最終ジャッジ日時: 2024-06-22 15:49:10
• 合計ジャッジ時間: 8,018 ms
• ジャッジサーバーID （参考情報）: judge1 / judge3

ファイルパターン	結果
sample	AC * 1
other	AC * 41

ソースコード

import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


struct Point(T) {
  T x, y;
  Pt opBinary(string op)(Pt a) const {
    static if (op == "+") return Pt(x + a.x, y + a.y);
    else static if (op == "-") return Pt(x - a.x, y - a.y);
    else static assert(false);
  }
  Pt opBinary(string op)(T k) const {
    static if (op == "*") return Pt(x * k, y * k);
    else static if (op == "/") return Pt(x / k, y / k);
    else static assert(false);
  }
  T dot(Pt a) const { return x * a.x + y * a.y; }
  T det(Pt a) const { return x * a.y - y * a.x; }
  int opCmp(Pt a) const { return (x < a.x) ? -1 : (x > a.x) ? +1 : (y < a.y) ? -1 : (y > a.y) ? +1 : 0; }
  string toString() const { return "(" ~ x.to!string ~ ", " ~ y.to!string ~ ")"; }
}

alias Pt = Point!long;
int sig(long r) {
  return cast(int)(sgn(r));
}
long tri(Pt a, Pt b, Pt c) {
  return (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
}

Pt[] convexHull(Pt[] ps) {
  auto qs = new Pt[ps.length + 1];
  ps.sort!((a, b) => ((a.x != b.x) ? (a.x < b.x) : (a.y < b.y)));
  int m = 0;
  foreach (p; ps) {
    for (; m > 1 && sig(tri(qs[m - 2], qs[m - 1], p)) <= 0; --m) {}
    qs[m++] = p;
  }
  const r = m;
  foreach_reverse (p; ps) {
    for (; m > r && sig(tri(qs[m - 2], qs[m - 1], p)) <= 0; --m) {}
    qs[m++] = p;
  }
  return qs[0 .. m - 1];
}


void main() {
  try {
    for (; ; ) {
      const N = readInt;
      auto P = new Pt[N];
      foreach (i; 0 .. N) {
        P[i].x = readLong;
        P[i].y = readLong;
      }
      
      const qs = P.convexHull;
      const qsLen = cast(int)(qs.length);
      
      long ans;
      long check(int i, int j) {
        if (j >= qsLen) j -= qsLen;
        const area = abs(qs[i].det(qs[j]));
        chmax(ans, area);
        return area;
      }
      
      for (int i = 0, j; i < qsLen; ++i) {
        for (; check(i, j) < check(i, j + 1); ++j) {}
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}