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package main
import (
"fmt"
"bufio"
"os"
"log"
)
type Point struct {
x,y int
}
type Triangle struct {
a,b,c Point
}
func readTriangle( str string ) (ret Triangle) {
fmt.Sscanf(str, "%d,%d,%d,%d,%d,%d", &ret.a.x, &ret.a.y, &ret.b.x, &ret.b.y, &ret.c.x, &ret.c.y)
return ret
}
func det( a, b Point) int {
return a.x*b.y - a.y*b.x;
}
func signe( c, a Point) bool {
return det(Point{ c.x - a.x, c.y - a.y}, Point{ -a.x, -a.y }) < 0
}
func main() {
file, err := os.Open("p102_triangles.txt")
cmp := 0
if err != nil {
log.Fatal(err)
}
defer file.Close()
scan := bufio.NewScanner(file)
scan.Split(bufio.ScanLines)
for scan.Scan() {
trian := readTriangle(scan.Text())
sign := signe( trian.c, trian.a )
if signe( trian.a, trian.b) == sign && signe( trian.b, trian.c ) == sign {
cmp++
}
}
fmt.Print(cmp);
}
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