Type of Triangle – 3024

🔗LC3024 🟢 Easy 🧩 Pattern – Array, math logic

You are given a 0-indexed integer array nums of size 3 which can form the sides of a triangle.

• A triangle is called equilateral if it has all sides of equal length.
• A triangle is called isosceles if it has exactly two sides of equal length.
• A triangle is called scalene if all its sides are of different lengths.

Return a string representing the type of triangle that can be formed or "none" if it cannot form a triangle.

Example

Example 1:

Input: nums = [3,3,3]
Output: "equilateral"
Explanation: Since all the sides are of equal length, therefore, it will form an equilateral triangle.

Example 2:

Input: nums = [3,4,5]
Output: "scalene"
Explanation: 
nums[0] + nums[1] = 3 + 4 = 7, which is greater than nums[2] = 5.
nums[0] + nums[2] = 3 + 5 = 8, which is greater than nums[1] = 4.
nums[1] + nums[2] = 4 + 5 = 9, which is greater than nums[0] = 3. 
Since the sum of the two sides is greater than the third side for all three cases, therefore, it can form a triangle.
As all the sides are of different lengths, it will form a scalene triangle.Code language: JavaScript (javascript)

Solution

First, we make sure the three sides form a valid triangle, and then find its type.

/**
 * @param {number[]} nums
 * @return {string}
 */
var triangleType = function (nums) {
    const [a, b, c] = nums;
    // Triangle: sum of any two sides must be greater than the third.
    if (!(a + b > c && a + c > b && b + c > a)) return "none";
    if (a === b && b === c) return "equilateral";
    if (a === b || a === c || b === c) return "isosceles";
    return "scalene";
};Code language: JavaScript (javascript)

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