41 lines
924 B
C++
41 lines
924 B
C++
#include<iostream>
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#include<stdio.h>
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using namespace std;
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const int Max = 110;
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struct Point
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{
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double x, y;
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};
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struct Segment
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{
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Point s, e;
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};
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Segment s[Max];
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double product(Point &a, Point &b, Point &c)
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{
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double x1, y1, x2, y2;
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x1 = a.x - c.x, y1 = a.y - c.y;
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x2 = b.x - c.x, y2 = b.y - c.y;
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return x1 * y2 - y1 * x2;
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}
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bool intersect(Segment &a, Segment &b)
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{
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return product(a.s, a.e, b.s) * product(a.s, a.e, b.e) <= 0 &&
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product(b.s, b.e, a.s) * product(b.s, b.e, a.e) <= 0;
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}
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int main()
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{
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int n, cnt;
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while(scanf("%d", &n) && n)
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{
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for(int i=0; i<n; i++)
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scanf("%lf %lf %lf %lf", &s[i].s.x, &s[i].s.y, &s[i].e.x, &s[i].e.y);
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cnt = 0;
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for(int i=0; i<n; i++)
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for(int j=i+1; j<n; j++)
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if(intersect(s[i], s[j])) cnt ++;
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printf("%d\n", cnt);
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}
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return 0;
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}
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