Two Sum Leetcode Solution

In, this tutorial we are going to solve leetcode Two Sum problem.

Problem statement

Given an array of integer nums and an integer target, return indices of the two numbers such that they add up to the target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

Example 1:

Input: nums = [2,7,11,15], target = 9
Output: [0,1]

Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2:

Input: nums = [3,2,4], target = 6
Output: [1,2]

Example 3:

Input: nums = [3,3], target = 6
Output: [0,1]


2 <= nums.length <= 104
-109 <= nums[i] <= 109
-109 <= target <= 109
Only one valid answer exists.



​class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        for i in range(len(nums)):
            for j in range(i+1, len(nums)):
                if (nums[i] + nums[j]) == target:
                    return [i, j]



step1: make a first loop that will run through the length of the array.

step2: Inside the first loop make another loop that will run one step index ahead till the length of the array.

step3: add an if statement to check the given condition as per the question and return them in the desired format of the list.