11657 - Rational Billiard/11657.cpp

   1 using namespace std;
   2 #include <algorithm>
   3 #include <iostream>
   4 #include <iterator>
   5 #include <numeric>
   6 #include <sstream>
   7 #include <fstream>
   8 #include <cassert>
   9 #include <climits>
  10 #include <cstdlib>
  11 #include <cstring>
  12 #include <string>
  13 #include <cstdio>
  14 #include <vector>
  15 #include <cmath>
  16 #include <queue>
  17 #include <deque>
  18 #include <stack>
  19 #include <list>
  20 #include <map>
  21 #include <set>
  22
  23 #define foreach(x, v) for (typeof (v).begin() x=(v).begin(); x !=(v).end(); ++x)
  24 #define For(i, a, b) for (int i=(a); i<(b); ++i)
  25 #define D(x) cout << #x " is " << x << endl
  26
  27 bool boom(int m, int n, int x0, int y0, int x1, int y1, int p, int q) {
  28     if (p == 0 or q == 0) {
  29         int c = p * (y1 - y0) - q * (x1 - x0);
  30         return (c == 0);
  31     }
  32     x0 *= abs(q), x1 *= abs(q), m *= abs(q);
  33     y0 *= abs(p), y1 *= abs(p), n *= abs(p);
  34     p /= abs(p);
  35     q /= abs(q);
  36
  37     int d1 = p * (y1 - y0)       - q * (x1 - x0);
  38     int d2 = p * (2*n - y1 - y0) - q * (x1 - x0);
  39     int d3 = p * (y1 - y0)       - q * (2*m - x1 - x0);
  40     int d4 = p * (2*n - y1 - y0) - q * (2*m - x1 - x0);
  41
  42     int g = __gcd(2*n*q, 2*m*p);
  43
  44     if (d1 % g == 0) return true;
  45     if (d2 % g == 0) return true;
  46     if (d3 % g == 0) return true;
  47     if (d4 % g == 0) return true;
  48     return false;
  49 }
  50
  51 int main(){
  52     int m, n, x0, y0, x1, y1, p, q;
  53     while (cin >> m >> n >> x0 >> y0 >> x1 >> y1 >> p >> q) {
  54         if (m == 0 and n == 0 and x0 == 0 and y0 == 0 and x1 == 0 and y1 == 0 and p == 0 and q == 0) break;
  55         if (boom(m, n, x0, y0, x1, y1, p, q)) {
  56             puts("HIT");
  57         } else {
  58             puts("MISS");
  59         }
  60     }
  61     return 0;
  62 }