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(n2)
time complexity?
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func twoSum(nums []int, target int) []int {
indexmap := make(map[int]int)
for currentIdx, currentNum := range nums {
if index, ok := indexmap[target-currentNum]; ok {
return []int{currentIdx, index}
}
indexmap[currentNum] = currentIdx
}
return []int{}
}
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