LeetCode in Kotlin
3899. Angles of a Triangle
Medium
You are given a positive integer array sides of length 3.
Determine if there exists a triangle with positive area whose three side lengths are given by the elements of sides.
If such a triangle exists, return an array of three floating-point numbers representing its internal angles (in degrees), sorted in non-decreasing order. Otherwise, return an empty array.
Answers within 10-5 of the actual answer will be accepted.
Example 1:
Input: sides = [3,4,5]
Output: [36.86990,53.13010,90.00000]
Explanation:
You can form a right-angled triangle with side lengths 3, 4, and 5. The internal angles of this triangle are approximately 36.869897646, 53.130102354, and 90 degrees respectively.
Example 2:
Input: sides = [2,4,2]
Output: []
Explanation:
You cannot form a triangle with positive area using side lengths 2, 4, and 2.
Constraints:
sides.length == 31 <= sides[i] <= 1000
Solution
import kotlin.math.acos
class Solution {
fun internalAngles(sides: IntArray): DoubleArray {
if (sides[0] + sides[1] <= sides[2] || sides[1] + sides[2] <= sides[0] || sides[0] + sides[2] <= sides[1]) {
return DoubleArray(0)
}
val angle = DoubleArray(sides.size)
angle[0] =
Math.toDegrees(
acos(
(
sides[1] * sides[1] +
sides[2] * sides[2] -
sides[0] * sides[0]
).toDouble() / (2 * sides[1] * sides[2]),
),
)
angle[1] =
Math.toDegrees(
acos(
(
sides[0] * sides[0] +
sides[2] * sides[2] -
sides[1] * sides[1]
).toDouble() / (2 * sides[0] * sides[2]),
),
)
angle[2] =
Math.toDegrees(
acos(
(
sides[1] * sides[1] +
sides[0] * sides[0] -
sides[2] * sides[2]
).toDouble() / (2 * sides[1] * sides[0]),
),
)
var max = angle[0]
var mid = 0.0
var min = 0.0
for (i in 1..<angle.size) {
if (angle[i] > max) {
min = mid
mid = max
max = angle[i]
} else {
if (angle[i] > mid) {
min = mid
mid = angle[i]
} else {
min = angle[i]
}
}
}
angle[0] = min
angle[1] = mid
angle[2] = max
return angle
}
}