Contents.swift

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/*:
 # 两个数组的交集
 
 - 题号：[349](https://leetcode-cn.com/problems/intersection-of-two-arrays/)
 - 难度：简单
 - 描述：
 
    给定两个数组，编写一个函数来计算它们的交集。
 */

//: ## Code
import Foundation

func intersection(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
    return Array(Set(nums1).intersection(Set(nums2)))
}

func intersection2(_ nums1: [Int], _ nums2: [Int]) -> [Int] {
    
    let _nums1 = nums1.sorted()
    let _nums2 = nums2.sorted()
    
    var left = 0
    var righ = 0
    
    var result: [Int] = []
    
    while left < _nums1.count && righ < _nums2.count {
        
        let _left = _nums1[left]
        let _righ = _nums2[righ]
        
        if _left == _righ {
            
            left += 1
            righ += 1
            
            if result.firstIndex(of: _left) == nil {
                result.append(_left)
            }
            
            continue
        }
        
        if _left < _righ {
            left += 1
        } else {
            righ += 1
        }
    }
    
    return result
}

//: ## Test
print(intersection2([1,2,2,1], [2,2])) // [2]
print(intersection2([4,9,5], [9,4,9,8,4])) // [9,4]

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