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LeetCode day315–3024

Everyday has one random leetcode quiz. Today’s quiz is 3024. Type of Triangle

Description:

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.

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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.

Given three side lengths aaa, bbb, and ccc, they can form a triangle if and only if the following three conditions are all satisfied

• A + B > C
• A + C > B
• B + C > A

The time complexity is O(1)

/**
 * @param {number[]} nums
 * @return {string}
 */
var triangleType = function (nums) {
    const isTriangle = nums[0] + nums[1] > nums[2]
        && nums[1] + nums[2] > nums[0]
        && nums[2] + nums[0] > nums[1]

    if (!isTriangle) {
        return 'none'
    }

    if (nums[0] === nums[1] && nums[1] === nums[2]) {
        return 'equilateral'
    } else if (nums[0] !== nums[1] && nums[0] !== nums[2] && nums[1] !== nums[2]) {
        return 'scalene'
    }

    return 'isosceles'
};