Is Integer to English Words easy or hard?

Integer to English Words is classified as a hard problem because it requires careful handling of multiple edge cases and number groupings. The algorithm itself is not computationally complex, but designing clean logic for hundreds, tens, teens, and large scale units makes the implementation challenging.

Integer to English Words Python/Java solution

Python solutions typically use recursion with helper functions to process values under 1000 and combine segments like thousands or millions. Java implementations often use iterative chunk processing with predefined arrays for number words. Both approaches run in O(log n) time and generate the final result using string concatenation or builders.

How to solve Integer to English Words in O(log n)?

Divide the number into chunks of three digits using division and modulo operations. Convert each chunk (0–999) into words using predefined mappings for numbers under 20 and multiples of ten, then append scale words like Thousand or Million. Process the chunks recursively or iteratively until the entire number is converted.

What is the best approach for Integer to English Words?

The recursive segmentation approach is widely considered the best. It splits the number into billions, millions, thousands, and hundreds, converting each segment recursively using word mappings for numbers under 20 and tens. This keeps the code clean and closely matches the structure of English number naming. Time complexity is O(log n) because the number is processed by digit groups.

Is Integer to English Words asked at Google/Amazon/Meta?

Integer to English Words has appeared in interviews at large tech companies including Google and Amazon because it tests recursion, string construction, and number decomposition. The problem checks whether candidates can break a large problem into reusable helper logic for smaller ranges like 0–999.

What data structure is used in Integer to English Words?

Most solutions rely on arrays or hash maps to store word mappings for numbers under 20, multiples of ten, and scale units like Thousand or Million. Recursion or iteration is used to process number segments, and strings or lists are used to build the final English phrase.

What is the time complexity of Integer to English Words?

The time complexity is O(log n), where n is the input number. The algorithm processes the number in groups of three digits (thousands, millions, billions). Since the maximum integer size is limited, the number of segments is small, making the runtime effectively constant for 32‑bit integers.

Description Hints 3 Solution Video 20:59

273. Integer to English Words

Hard34.9% acceptance24 companies

Convert a non-negative integer num to its English words representation.

Example 1:

Input: num = 123
Output: "One Hundred Twenty Three"

Example 2:

Input: num = 12345
Output: "Twelve Thousand Three Hundred Forty Five"

Example 3:

Input: num = 1234567
Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"

Constraints:

0 <= num <= 2³¹ - 1

Asked at top 20 of 24 companies

Zscaler WarnerMedia Delhivery Gusto Faire Roblox Fractal Analytics Palantir Attentive Amazon Microsoft Apple

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Hints open one at a time

Hint 1

Did you see a pattern in dividing the number into chunk of words? For example, 123 and 123000.

Hint 2

Group the number by thousands (3 digits). You can write a helper function that takes a number less than 1000 and convert just that chunk to words.

Hint 3

There are many edge cases. What are some good test cases? Does your code work with input such as 0? Or 1000010? (middle chunk is zero and should not be printed out)

20:59

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