POJ 2318 叉积 + 枚举

code:

#include <iostream>#include <cstring>using namespace std;const int N = 5000 + 10;int Ui[N], Li[N], ans[N];int n, m, x1, y1, x2, y2, up, down, x, y;bool check(int x, int y, int ux, int uy, int dx, int dy){return (ux - x) * (dy - y) - (dx - x) * (uy - y) > 0;}int main(){bool f = 0;while(cin >> n, n){memset(ans, 0, sizeof ans);cin >> m >> x1 >> y1 >> x2 >> y2;if(f) cout << endl;else f = 1;for(int i = 1; i <= n; ++i) cin >> Ui[i] >> Li[i];Ui[0] = Li[0] = x1;Ui[n + 1] = Li[n + 1] = x2;for(int i = 1; i <= m; ++i){cin >> x >> y;for(int j = 0; j <= n; ++j){if(check(x, y, Ui[j], y1, Li[j], y2) && !check(x, y, Ui[j + 1], y1, Li[j + 1], y2)){++ans[j];break;}}}for(int i = 0; i <= n; ++i) cout << i << ": " << ans[i] << endl;}return 0;}