Find Three Consecutive Integers That Sum to a Given Number Python/Java solution

In Python or Java, compute mid = num // 3 after verifying num % 3 == 0. Return [mid - 1, mid, mid + 1]. If the modulo check fails, return an empty list or array. The implementation is only a few lines and runs in O(1) time.

What is the best approach for Find Three Consecutive Integers That Sum to a Given Number?

The optimal approach uses an algebraic observation. Three consecutive integers can be written as x-1, x, and x+1, whose sum equals 3x. If num is divisible by 3, the middle integer is num/3 and the result is [x-1, x, x+1]. This solution runs in O(1) time and O(1) space.

Is Find Three Consecutive Integers That Sum to a Given Number asked at Google/Amazon/Meta?

This problem represents a common interview pattern where mathematical properties simplify brute-force thinking. Similar math-based reasoning questions appear in interviews at companies like Amazon, Google, and Microsoft, especially for testing pattern recognition and number manipulation.

What data structure is used in Find Three Consecutive Integers That Sum to a Given Number?

No complex data structure is required. The solution relies on simple arithmetic and returns a small array or list containing three integers. The core concept comes from mathematical reasoning rather than data structure manipulation.

What is the time complexity of Find Three Consecutive Integers That Sum to a Given Number?

The optimal solution runs in O(1) time because it performs only a modulo check and constant arithmetic operations. No loops or recursion are required. Space complexity is also O(1) since only three integers are returned.

Description Hints 2 Solution Video 5:09

2177. Find Three Consecutive Integers That Sum to a Given Number

Q: Is Find Three Consecutive Integers That Sum to a Given Number easy or hard?

LeetCode classifies this problem as Medium, but the difficulty mainly comes from spotting the mathematical relationship. Once you realize the sum of three consecutive integers equals 3x, the solution becomes a straightforward constant-time calculation.

Q: How to solve Find Three Consecutive Integers That Sum to a Given Number in O(1)?

Check whether the given number is divisible by 3 using num % 3. If it is not divisible, no valid triple exists. If it is divisible, compute mid = num / 3 and return [mid - 1, mid, mid + 1]. The computation uses constant arithmetic operations, giving O(1) time complexity.

Medium65.3% acceptance1 company

Given an integer num, return three consecutive integers (as a sorted array) that sum to num. If num cannot be expressed as the sum of three consecutive integers, return an empty array.

Example 1:

Input: num = 33
Output: [10,11,12]
Explanation: 33 can be expressed as 10 + 11 + 12 = 33.
10, 11, 12 are 3 consecutive integers, so we return [10, 11, 12].

Example 2:

Input: num = 4
Output: []
Explanation: There is no way to express 4 as the sum of 3 consecutive integers.

Constraints:

0 <= num <= 10¹⁵

Asked at 1 company

Fpt

Topics

Math Simulation

Hints open one at a time

Hint 1

Notice that if a solution exists, we can represent them as x-1, x, x+1. What does this tell us about the number?

Hint 2

Notice the sum of the numbers will be 3x. Can you solve for x?

5:09

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