Problem: Valid Triangle Number

med

30 min

Understand how to determine the number of triplets in an array that can form valid triangles. Learn to apply sorting with two-pointer or binary search methods to solve this common coding interview pattern efficiently.

Statement

Given an array of integers, nums, determine the number of triplets of distinct indices (i, j, k) that can be selected from the array such that the values at those indices can form the sides of a valid triangle.

Return this count as the result.

Note: The triplet of indices is treated as an unordered combination, not a permutation. For example, indices (0, 1, 2) and (2, 1, 0) represent the same triplet and should be counted once.

Constraints:

$1 <=$ nums.length $<= 1000$
$0 <=$ nums[i] $<= 1000$

Problem: Valid Triangle Number

med

30 min

Statement

Return this count as the result.

Note: The triplet of indices is treated as an unordered combination, not a permutation. For example, indices (0, 1, 2) and (2, 1, 0) represent the same triplet and should be counted once.

Constraints:

$1 <=$ nums.length $<= 1000$
$0 <=$ nums[i] $<= 1000$

Problem: Valid Triangle Number

Statement

Examples

Understand the problem

Figure it out!

Try it yourself

Problem: Valid Triangle Number

Statement

Examples

Understand the problem

Figure it out!

Try it yourself