Two Sum (Leetcode 1) (DCP 1)

Problem Link: https://leetcode.com/problems/two-sum/

Brute force Approach

TC: O(N2) SC: O(1)

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]: 
        length=len(nums)
        for idx1 in range(n-1):
            for idx2 in range(idx1+1,length):
                if(nums[idx1]+nums[idx2]==target):
                    return [idx1,idx2]

Hashing Approach

TC: O(N) SC: O(N)

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:   
        dictionary={}
        for idx in range(len(nums)):
            if(target-nums[idx] in dictionary):
                return [idx,dictionary[target-nums[idx]]]
            dictionary[nums[i]]=i