42 lines
812 B
Markdown
42 lines
812 B
Markdown
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# 1. Two Sum (Easy)
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Given an array of integers `nums` and an integer `target`, return _indices of
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the two numbers such that they add up to `target`_.
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You may assume that each input would have exactly **one solution**, and you may
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not use the _same_ element twice.
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You can return the answer in any order.
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## Example 1:
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```
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Input: nums = [2,7,11,15], target = 9
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Output: [0,1]
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Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].
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```
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## Example 2:
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```
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Input: nums = [3,2,4], target = 6
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Output: [1,2]
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```
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## Example 3:
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```
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Input: nums = [3,3], target = 6
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Output: [0,1]
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```
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## Constraints:
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- 2 <= nums.length <= 10^4
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- -10^9 <= nums[i] <= 10^9
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- -10^9 <= target <= 10^9
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- **Only one valid answer exists.**
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Follow-up: Can you come up with an algorithm that is less than `O(n^2)` time
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complexity?
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