20201210.md

Algorithm

349. Intersection of Two Arrays

Description

Given two arrays, write a function to compute their intersection.

Example 1:

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]

Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]

Note:

• Each element in the result must be unique.
• The result can be in any order.

Solution

class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        Set<Integer> set = new HashSet<>();
        List<Integer> list = new ArrayList<>();
        for(int i=0;i<nums1.length;i++){
            set.add(nums1[i]);
        }
        for(int i=0; i<nums2.length; i++){
            if(set.contains(nums2[i])){
                list.add(nums2[i]);
                set.remove(nums2[i]);
            }
        }
        int[] result = new int[list.size()];
        for(int i=0;i<result.length;i++){
            result[i] = list.get(i);
        }
        return result;
    }
}

class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        Set<Integer> set = new HashSet<>();
        Set<Integer> setResult = new HashSet<>();
        for(int i=0;i<nums1.length;i++){
            set.add(nums1[i]);
        }
        for(int i=0; i<nums2.length; i++){
            if(set.contains(nums2[i])){
                setResult.add(nums2[i]);
            }
        }
        int[] result = new int[setResult.size()];
        int k=0;
        for(Integer value:setResult){
            result[k++] = value;
        }
        return result;
    }
}

Discuss

两个Set集合即可

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