LeetCode-in-Java
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
public class Solution {
public double[] internalAngles(int[] sides) {
if (sides[0] + sides[1] <= sides[2]
|| sides[1] + sides[2] <= sides[0]
|| sides[0] + sides[2] <= sides[1]) {
return new double[0];
}
double[] angle = new double[sides.length];
angle[0] =
Math.toDegrees(
Math.acos(
(double)
(sides[1] * sides[1]
+ sides[2] * sides[2]
- sides[0] * sides[0])
/ (2 * sides[1] * sides[2])));
angle[1] =
Math.toDegrees(
Math.acos(
(double)
(sides[0] * sides[0]
+ sides[2] * sides[2]
- sides[1] * sides[1])
/ (2 * sides[0] * sides[2])));
angle[2] =
Math.toDegrees(
Math.acos(
(double)
(sides[1] * sides[1]
+ sides[0] * sides[0]
- sides[2] * sides[2])
/ (2 * sides[1] * sides[0])));
double max = angle[0];
double mid = 0;
double min = 0;
for (int i = 1; i < angle.length; i++) {
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;
}
}