LeetCode #1: Two Sum

Problem Statement

(Problem Link) Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Solution

class Solution(object):
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
indexed_map = dict()
for i, v in enumerate(nums):
if target - v in indexed_map:
return [indexed_map[target - v], i]
else:
indexed_map[v] = i

Time complexity: O(n)

Space complexity: O(1)