Swift 两数之和 - LeetCode

给定一个整数数列，找出其中和为特定值的那两个数。

你可以假设每个输入都只会有一种答案，同样的元素不能被重用。

给定 nums = [2, 7, 11, 15], target = 9

因为 nums[0] + nums[1] = 2 + 7 = 9
所以返回 [0, 1]

class Solution {
    func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
        let count = nums.count
        for i in 0..<count {
            for j in (i + 1)..<count {
                if nums[i] + nums[j] == target {
                    return [i,j]
                }
            }
        }
        return []
    }
}

class Solution {
    func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
        let count = nums.count
     
        var dic = [Int : Int]()
        
        for i in 0..<count {
            dic[nums[i]] = i
        }
        
        for i in 0..<count {
            let found = target - nums[i]
            if let j = dic[found], i != j {
                return [i, j]
            }
        }
        return []
    }
}