# LeetCode-Two Sum

#### 问题

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 <= 10`3
• `-10`9` <= nums[i] <= 10`9
• `-10`9` <= target <= 10`9
• Only one valid answer exists.

#### 解答：

```class Solution:
def twoSum(self, nums: List[int], target: int) -> List[int]:
dict = {}
for index, value in enumerate(nums):
remaining = target-value
if remaining in dict:
return [dict[remaining], index]
dict[value] = index
return []

```

#### 参考及引用

https://leetcode.com/problems/two-sum/solution/

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