Topic links: 1058. extrusion die
The meaning of problems
And a given volume of the mold bottom, high demand mold.
Thinking
Bottom mold is a polygon, the polygon area thus determined, the volume is divided by the area of the bottom of the answer.
Solving see areas of the polygons EOJ 1127. polygon area (Computational Geometry)
Code
#include <cstdio>
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
using namespace std;
typedef long long ll;
typedef double db;
const db eps = 1e-10;
const db pi = acos(-1.0);
const ll inf = 0x3f3f3f3f3f3f3f3f;
const ll maxn = 100 + 10;
inline int dcmp(db x) {
if(fabs(x) < eps) return 0;
return x > 0? 1: -1;
}
class Point {
public:
double x, y;
Point(double x = 0, double y = 0) : x(x), y(y) {}
void input() {
scanf("%lf%lf", &x, &y);
}
bool operator<(const Point &a) const {
return (!dcmp(x - a.x))? dcmp(y - a.y) < 0: x < a.x;
}
bool operator==(const Point &a) const {
return dcmp(x - a.x) == 0 && dcmp(y - a.y) == 0;
}
db dis2(const Point a) {
return pow(x - a.x, 2) + pow(y - a.y, 2);
}
db dis(const Point a) {
return sqrt(dis2(a));
}
db dis2() {
return x * x + y * y;
}
db dis() {
return sqrt(dis2());
}
Point operator+(const Point a) {
return Point(x + a.x, y + a.y);
}
Point operator-(const Point a) {
return Point(x - a.x, y - a.y);
}
Point operator*(double p) {
return Point(x * p, y * p);
}
Point operator/(double p) {
return Point(x / p, y / p);
}
db dot(const Point a) {
return x * a.x + y * a.y;
}
db cross(const Point a) {
return x * a.y - y * a.x;
}
};
Point p[maxn];
int n;
db area() {
if(n < 3) return 0.0;
db ans = 0.0;
for(int i = 2; i < n; ++i) {
ans += (p[i] - p[1]).cross(p[i + 1] - p[1]);
}
return ans * 0.5;
}
int main() {
while(~scanf("%d", &n) && n) {
db s = 0;
db v;
for(int i = 1; i <= n; ++i) {
p[i].input();
}
scanf("%lf", &v);
s = area();
printf("BAR LENGTH: %.2lf\n", v / fabs(s));
}
return 0;
}