问题描述
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]
Output: 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 <= 103
-109 <= nums[i] <= 109
-109 <= target <= 109
- Only one valid answer exists.
自己写的暴力解法
def two_sum(nums, target)
for i in 0...nums.size
for j in (i+1)...nums.size
if nums[i] + nums[j] == target
puts i, j
return [i, j]
end
end
end
end
虽然能用,但是不优雅
别人家的优雅解法
def two_sum(nums, target)
map = {}
nums.each_with_index { |val, index|
n = target - val
if map.include?(n)
return [map[n], index]
else
map[val] = index
end
}
end
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