UVa/270 - Lining Up/270.cpp

   1 /*
   2   Problem: 270 - Lining up
   3   Andrés Mejía-Posada (andmej@gmail.com)
   4
   5   Time limit exceeded.
   6 */
   7 using namespace std;
   8 #include <algorithm>
   9 #include <iostream>
  10 #include <iterator>
  11 #include <sstream>
  12 #include <fstream>
  13 #include <cassert>
  14 #include <climits>
  15 #include <cstdlib>
  16 #include <cstring>
  17 #include <string>
  18 #include <cstdio>
  19 #include <vector>
  20 #include <cmath>
  21 #include <queue>
  22 #include <deque>
  23 #include <stack>
  24 #include <list>
  25 #include <map>
  26 #include <set>
  27
  28 #define D(x) cout << #x " is " << x << endl
  29
  30 struct point{
  31   int x, y;
  32   point(int x=0, int y=0) : x(x), y(y) {}
  33 };
  34
  35 inline void simplify(pair<int, int> &p){
  36   #define x first
  37   #define y second
  38   if (p.y == 0){
  39     p.x = 1;
  40     return;
  41   }
  42   if (p.x == 0){
  43     p.y = 1;
  44     return;
  45   }
  46   int sign = ((p.x<0)^(p.y<0) ? -1 : 1);
  47   if (p.x < 0) p.x *= -1;
  48   if (p.y < 0) p.y *= -1;
  49   int g = __gcd(p.x, p.y);
  50   if (g) p.x /= g, p.y /= g;
  51   p.x *= sign;
  52   #undef x
  53   #undef y
  54 }
  55
  56 char buf[512];
  57
  58 int main(){
  59   int cases;
  60   fgets(buf, 512, stdin);
  61   sscanf(buf, "%d", &cases);
  62   fgets(buf, 512, stdin);
  63   while (cases--){
  64     vector<point> p;
  65     while (fgets(buf, 512, stdin) != NULL && strcmp(buf, "\n")){
  66       point _;
  67       sscanf(buf, "%d %d", &_.x, &_.y);
  68       p.push_back(_);
  69     }
  70
  71     int x = 0;
  72     map<pair<int, int>, int> cnt;
  73     const int n = p.size();
  74     for (int i=0; i<n; ++i){
  75       for (int j=i+1; j<n; ++j){
  76         pair<int, int> slope(p[j].y - p[i].y, p[j].x - p[i].x);
  77         simplify(slope);
  78         x = max(x, ++cnt[slope]);
  79       }
  80     }
  81
  82     printf("%d\n", (int)((1 + sqrt(1 + 8*x))/2));
  83     if (cases > 0) puts("");
  84   }
  85   return 0;
  86 }