# 57.和为s的两个数字

### 一、 题目

输入一个递增排序的数组和一个数字s，在数组中查找两个数，使得它们的和正好是s。如果有多对数字的和等于s，则输出任意一对即可。

示例 1：

输入：nums = \[2,7,11,15], target = 9

输出：\[2,7] 或者 \[7,2]

示例 2：

输入：nums = \[10,26,30,31,47,60], target = 40

输出：\[10,30] 或者 \[30,10]

限制：

1 <= nums.length <= 10^5

1 <= nums\[i] <= 10^6

来源：力扣（LeetCode）

链接：<https://leetcode-cn.com/problems/he-wei-sde-liang-ge-shu-zi-lcof>

著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

### 二、 解法

#### 2.1 Map

```
func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
    var temp: [Int : Int] = [:]
    for num in nums {
        guard target >= num else { break }
        if let other = temp[num] {
            return [num, other]
        }
        temp[target - num] = num
    }
    return []
}
```

#### 2.2 双指针

```
func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
    var l = 0, r = nums.count - 1
    
    while l < r {
        let a = nums[l], b = nums[r]
        if a + b > target {
            r -= 1
        }
        else if a + b < target {
            l += 1
        }
        else {
            return [a, b]
        }
    }
    
    return []
}
```


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