Problem

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:

  1. Input: nums = [2,7,11,15], target = 9
  2. Output: [0,1]
  3. Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2:

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

Example 3:

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

Solution

遍历数组:

  1. 用一个map存已遍历的元素，以及对应的index
  2. 遍历到新的元素的时候去check，map中是否有target-ele的key