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Calculate Amount Paid in Taxes - Solution & Explanation

EasyArraySimulation12 min readAsked at: Meta, Oracle, Interactive Brokers +3
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Problem Statement

You are given a 0-indexed 2D integer array brackets where brackets[i] = [upperi, percenti] means that the ith tax bracket has an upper bound of upperi and is taxed at a rate of percenti. The brackets are sorted by upper bound (i.e. upperi-1 < upperi for 0 < i < brackets.length).

Tax is calculated as follows:

  • The first upper0 dollars earned are taxed at a rate of percent0.
  • The next upper1 - upper0 dollars earned are taxed at a rate of percent1.
  • The next upper2 - upper1 dollars earned are taxed at a rate of percent2.
  • And so on.

You are given an integer income representing the amount of money you earned. Return the amount of money that you have to pay in taxes. Answers within 10-5 of the actual answer will be accepted.

 

Example 1:

Input: brackets = [[3,50],[7,10],[12,25]], income = 10
Output: 2.65000
Explanation:
Based on your income, you have 3 dollars in the 1st tax bracket, 4 dollars in the 2nd tax bracket, and 3 dollars in the 3rd tax bracket.
The tax rate for the three tax brackets is 50%, 10%, and 25%, respectively.
In total, you pay $3 * 50% + $4 * 10% + $3 * 25% = $2.65 in taxes.

Example 2:

Input: brackets = [[1,0],[4,25],[5,50]], income = 2
Output: 0.25000
Explanation:
Based on your income, you have 1 dollar in the 1st tax bracket and 1 dollar in the 2nd tax bracket.
The tax rate for the two tax brackets is 0% and 25%, respectively.
In total, you pay $1 * 0% + $1 * 25% = $0.25 in taxes.

Example 3:

Input: brackets = [[2,50]], income = 0
Output: 0.00000
Explanation:
You have no income to tax, so you have to pay a total of $0 in taxes.

 

Constraints:

  • 1 <= brackets.length <= 100
  • 1 <= upperi <= 1000
  • 0 <= percenti <= 100
  • 0 <= income <= 1000
  • upperi is sorted in ascending order.
  • All the values of upperi are unique.
  • The upper bound of the last tax bracket is greater than or equal to income.

Approach Overview

Problem Overview: You are given progressive tax brackets where each bracket defines an upper income limit and the percentage tax applied to that portion of income. The task is to compute the total tax paid for a given income by applying each bracket sequentially until the income limit is reached.

Approach 1: Iterative Calculation of Taxes by Bracket (O(n) time, O(1) space)

This approach directly simulates how progressive taxes are calculated in real systems. Iterate through the brackets array and determine how much of your income falls inside the current bracket. For each bracket, compute the taxable portion as min(income, upperLimit) - previousLimit, multiply it by the tax percentage, and accumulate the result. Update the previous limit as you move to the next bracket. Once the income falls below the current bracket's upper limit, the remaining tax can be computed and the loop stops. This method uses only simple arithmetic and a single pass through the array, making it ideal for problems involving array traversal and direct simulation.

Approach 2: Cumulative Summation with Early Exit (O(n) time, O(1) space)

This variation also processes brackets sequentially but focuses on accumulating the taxable income incrementally. Instead of recalculating limits repeatedly, track the remaining income and process each bracket's capacity. For each bracket, determine how much income can be taxed inside that range and add the computed tax to a running total. If the remaining income becomes zero or negative, break early since no further brackets apply. The early exit avoids unnecessary iterations when income lies within lower brackets. The algorithm still runs in linear time relative to the number of brackets and requires constant extra memory.

Recommended for interviews: The iterative bracket simulation is the expected solution. Interviewers want to see that you correctly model progressive tax calculation and handle bracket boundaries without off‑by‑one mistakes. Both implementations run in O(n) time with O(1) space, but the direct bracket iteration clearly demonstrates your understanding of range processing and controlled iteration over arrays.

Approach 1: Iterative Calculation of Taxes by Bracket

This approach involves iterating through each tax bracket and calculating the tax for each, based on the remaining income. We begin taxing from the first dollar and proceed until all income is subject to tax based on the relevant brackets.

In Python, the function calculateTax iteratively computes the tax by subtracting from the income the amount taxed at each bracket. The variable previous_upper tracks the upper boundary of the last considered bracket to determine the current bracket size.

Code

PythonC++JavaC#JavaScript

Python

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Java

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JavaScript

Complexity

Time Complexity: O(n), where n is the number of tax brackets.
Space Complexity: O(1), since only a few auxiliary variables are used.

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Approach 2: Cumulative Summation with Early Exit

This approach involves iterating through each bracket while cumulatively summing the taxes, and exiting early if the full income has been taxed. It uses a cumulative difference strategy where each bracket contributes only the difference from the previous bracket.

In this Python solution, the algorithm checks if there's any income left to tax before continuing with processing a new bracket. It ensures minimal computation by bounding taxable income calculation by using min on upper and income.

Code

PythonC++JavaC#JavaScript

Python

C++

Java

C#

JavaScript

Complexity

Time Complexity: O(n), with n being the number of brackets.
Space Complexity: O(1), as no additional space proportionate to input size is required.

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Approach 3: Simulation

We traverse brackets, and for each tax bracket, we calculate the tax amount for that bracket, then accumulate it.

The time complexity is O(n), where n is the length of brackets. The space complexity is O(1).

Code

PythonJavaC++GoTypeScriptRust

Python

Java

C++

Go

TypeScript

Rust

Try this approach in the editor →

Complexity Comparison

ApproachComplexity
Iterative Calculation of Taxes by Bracket

Time Complexity: O(n), where n is the number of tax brackets.
Space Complexity: O(1), since only a few auxiliary variables are used.

Cumulative Summation with Early Exit

Time Complexity: O(n), with n being the number of brackets.
Space Complexity: O(1), as no additional space proportionate to input size is required.

Simulation—

Detailed Complexity Analysis

ApproachTimeSpaceWhen to Use
Iterative Calculation of Taxes by BracketO(n)O(1)Standard solution when simulating progressive tax brackets
Cumulative Summation with Early ExitO(n)O(1)Useful when income often falls in lower brackets and early termination saves iterations

Video Solution

2303. Calculate Amount Paid in Taxes (Leetcode Easy) • Programming Live with Larry • 791 views views

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Frequently Asked Questions

Is Calculate Amount Paid in Taxes easy or hard?
Calculate Amount Paid in Taxes is classified as an Easy problem. The challenge mainly involves correctly handling bracket boundaries and applying the tax percentage to the correct portion of income using simple array iteration.
Calculate Amount Paid in Taxes Python/Java solution
The solution in Python or Java follows the same logic: iterate through each bracket, compute the taxable portion of income within that range, multiply by the tax percentage, and accumulate the total. Both implementations run in O(n) time with constant extra space.
How to solve Calculate Amount Paid in Taxes in O(n)?
Traverse the brackets sequentially and determine how much of the income lies inside each bracket range. Compute the taxable portion using the difference between the current upper limit and the previous limit. Multiply that portion by the tax rate and accumulate the result until the income is fully processed.
What is the best approach for Calculate Amount Paid in Taxes?
The best approach is iterating through the tax brackets and computing the taxable portion for each range. For every bracket, calculate the income portion within that range and multiply it by the given tax percentage. This simulation runs in O(n) time and O(1) space, where n is the number of brackets.
Is Calculate Amount Paid in Taxes asked at Google/Amazon/Meta?
Problems involving progressive ranges and simulation frequently appear in coding interviews at large tech companies. While this exact problem is common on LeetCode, similar array simulation questions are used by companies like Amazon and Google to test basic algorithmic reasoning.
What data structure is used in Calculate Amount Paid in Taxes?
The primary data structure is an array that stores tax brackets as pairs of values: upper income limit and tax percentage. The algorithm iterates through the array sequentially and performs arithmetic calculations for each bracket.
What is the time complexity of Calculate Amount Paid in Taxes?
The time complexity is O(n) because the algorithm processes each tax bracket once. Space complexity is O(1) since only a few variables are used to track the previous limit, current taxable income, and accumulated tax.

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