Practise algorithms and data structures, test your solutions in the browser and track your progress over time.
def two_sum(nums, target):
seen = {}
for index, value in enumerate(nums):
difference = target - value
if difference in seen:
return [seen[difference], index]
seen[value] = index
Accepted
25 / 25 test cases passed
150+
Coding problems
4
Supported languages
Instant
Test feedback
How Codey works
Choose a challenge, test your approach, then submit your solution and keep track of what you have solved.
01
Pick from problems across different topics and difficulty levels, then work through the description and examples.
Two Sum
Arrays · Hash Table
Given an array of integers nums and an integer target, return the indices of the two numbers that add up to the target.
nums = [2, 7, 11, 15]
target = 9
Test cases
Input
nums = [2, 7, 11, 15] target = 9
Result
Output
Test case 1
Test case 2
02
Write code directly in the browser and check it against provided or custom test cases before submitting.
03
Submit against the larger number of test cases, revisit previous attempts and see your progress build over time.
Accepted
25 / 25 test cases passed
Problems solved
47
Submissions
86
Acceptance rate
54.7%
Create an account to save submissions, revisit your solutions and track your progress.
Log in or sign up