1. Two Sum - Easy

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

 

Constraints:

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

 

Follow-up: Can you come up with an algorithm that is less than O(n2time complexity?


Hints:


class Solution(object):
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """


        values = []
        [values.append([num, i]) for i, num in enumerate(nums)]
        values.sort()
        start, end = 0, len(nums)-1
        while start<end:
            current = values[start][0] + values[end][0]
            if target == current:
                return [values[start][1], values[end][1]]
            elif current < target:
                start+=1
            else:
                end -=1

Random Note


LRUCache can be implemented - Hashmap + Doubly Linked List - Python Dict/OrderDict - HashMap + List At least I've tested them for fun :p