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## Discussion of Problem 1710. Boris, You Are Wrong!

help, WA 44
Posted by zerumi 22 Jul 2024 22:45
I'm the first one, who stuck on this test, my program written in Kotlin (probably, same rules applies to Java).
I don't understand, what is "maximum precision"? Should I use double, float or maybe bigdecimal?

My program calculates side lengths, area of the triangle (via sides), angles (via sides and acos), and result point C_2.

Any help is really welcome!

import kotlin.math.*

class Point(val x: Int, val y: Int) {

constructor(raw: String) :
this(raw.split(' ')[0].toInt(), raw.split(' ')[1].toInt())

override fun toString(): String = "\$x \$y"
}

class Vector(p1: Point, p2: Point) {
private val x = p1.x - p2.x
private val y = p1.y - p2.y
fun length(): Double = sqrt((x*x + y*y).toDouble())
}

fun angle(v1: Vector, v2: Vector, v3: Vector): Double =
acos(
(v1.length().pow(2) + v2.length().pow(2) - v3.length().pow(2))
/ (2 * v1.length() * v2.length())
)

fun triangleSquare(v1: Vector, v2: Vector, v3: Vector): Double {
val halvedSideSum = (v1.length() + v2.length() + v3.length()) / 2.0
return sqrt(
halvedSideSum *
(halvedSideSum - v1.length()) *
(halvedSideSum - v2.length()) *
(halvedSideSum - v3.length())
)
}

fun Double.fuzzyEquals(other: Double): Boolean = (abs(this - other) < 1e-10)

fun Double.fuzzyEqualsLow(other: Double): Boolean = (abs(this - other) < 1e-4)

fun main() {
// input

// solution
val fixedPointA = Point(0, 0)
val fixedPointB = Point(pointB.x - pointA.x, pointB.y - pointA.y)
val fixedPointC = Point(pointC.x - pointA.x, pointC.y - pointA.y)

val sideAB = Vector(fixedPointA, fixedPointB)
val sideBC = Vector(fixedPointB, fixedPointC)
val sideAC = Vector(fixedPointA, fixedPointC)

val angleBAC = angle(sideAB, sideAC, sideBC)
val angleACB = angle(sideAC, sideBC, sideAB)
val angleCBA = angle(sideBC, sideAB, sideAC)

// find h
val h = 2.0 / sideAC.length() * triangleSquare(sideAB, sideBC, sideAC)
// tan ACB = h / x
val x = h / tan(angleACB)
val subtractVectorLength = 2.0 * x
val ratio = (sideAC.length() - subtractVectorLength) / sideAC.length()

if (ratio <= 0.0 || ratio.fuzzyEquals(0.0) || ratio.fuzzyEqualsLow(1.0)) println("YES")
else {
println("NO")
println(fixedPointA)
println(fixedPointB)
println(
"%.20f".format(fixedPointC.x * ratio) +
" \${"%.20f".format(fixedPointC.y * ratio)}")
}
}

Edited by author 22.07.2024 22:53