POJ 2318 叉积 + 枚举

code:

#include <iostream>
#include <cstring>
using namespace std;

const int N = 5000 + 10;

int Ui
, Li
, ans
;
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;
}