Largest Perimeter Triangle
A easy-tier problem at 57% community acceptance, tagged with Array, Math, Greedy. Reported in interviews at Tesla and 0 others.
Largest Perimeter Triangle hits your screen and you might overthink it. You've got an array of integers, need to find three that form a valid triangle with the largest perimeter. Tesla has asked this. The trap: candidates waste time trying every combination or sorting wrong. The pattern is dead simple once you see it, but blank-out-syndrome is real in a live OA. If you freeze on the greedy insight, StealthCoder solves it in seconds, invisible to the proctor, and you move on.
Companies that ask "Largest Perimeter Triangle"
Largest Perimeter Triangle is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe trick is sorting the array in descending order, then iterating left to right. For any three consecutive numbers where the largest is first, if the sum of the two smaller numbers beats the largest, you have a valid triangle (the triangle inequality is satisfied and no other combo will beat that perimeter). Most candidates either try a brute-force triple loop or forget that consecutive elements in a sorted array give you the maximum perimeter fastest. The math is light, the greedy move is the whole problem. Common miss: not recognizing that you can stop at the first valid triplet instead of checking all pairs. When this problem appears on your assessment and you're stuck on why brute-force feels clunky, StealthCoder surfaces the sorted greedy approach instantly.
Pattern tags
You know the problem.
Make sure you actually pass it.
Largest Perimeter Triangle recycles across companies for a reason. It's easy-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Largest Perimeter Triangle interview FAQ
Why does sorting descending help here?+
A sorted array lets you grab the three largest numbers greedily. The first valid triplet you find has the max perimeter because larger numbers always win. No need to check smaller combinations once you've got a valid triangle from the top.
What's the triangle inequality rule I need to remember?+
For three sides a, b, c to form a triangle, the sum of any two must be greater than the third. After sorting descending, you only check if a + b > c. The other two inequalities are automatically true.
Is this problem still asked after it became easy-tier?+
Yes. Tesla has asked it. Easy-tier problems are screening filters, not gimmes. Companies use them to eliminate candidates who panic or over-engineer. Know the greedy pattern and you pass this gate fast.
What if no valid triangle exists in the array?+
Return 0 or -1 depending on the problem statement. After sorting, if no three consecutive elements form a valid triangle, no three elements in the array will. No need to backtrack.
How does this relate to the other topics listed?+
Array work is iterating the sorted input. Math is the triangle inequality check. Greedy is the key: stop at the first valid triplet from the top. Sorting makes the greedy move work. Each topic is a single step.
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