题目传送门
1 /* 2 水题，就是用三点共线的式子来判断射击次数 3 */ 4 #include <cstdio> 5 #include <cmath> 6 #include <string> 7 #include <cstring> 8 #include <iostream> 9 #include <algorithm> 10 #include <map> 11 #include <set> 12 #include <vector> 13 using namespace std; 14 15 const int MAXN = 1e3 + 10; 16 int x[MAXN], y[MAXN]; 17 bool used[MAXN]; 18 19 int main(void) 20 { 21 //freopen ("B.in", "r", stdin); 22 23 int n, x0, y0; 24 25 while (~scanf ("%d%d%d", &n, &x0, &y0)) 26 { 27 memset (used, 0, sizeof (used)); 28 29 for (int i=1; i<=n; ++i) 30 { 31 scanf ("%d%d", &x[i], &y[i]); 32 x[i] -= x0; y[i] -= y0; 33 } 34 35 int cnt = 0; 36 for (int i=1; i<=n; ++i) 37 { 38 if (!used[i]) 39 { 40 cnt++; 41 for (int j=i; j<=n; ++j) 42 { 43 if (!used[j] && (x[i] * y[j] == x[j] * y[i])) 44 used[j] = 1; 45 } 46 } 47 } 48 49 printf ("%d\n", cnt); 50 } 51 52 return 0; 53 }
