[leetcode] 349. Intersection of Two Arrays 解题报告

题目链接: https://leetcode.com/problems/intersection-of-two-arrays/

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

Example:
Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].

Note:

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

思路: 简单hashtable, 先把一个数组放到hashtable中, 然后查另外一个数组, 如果碰到相同的就加入结果集合, 并且删除其hashtable.

代码如下:

class Solution {
public:
    vector intersection(vector& nums1, vector& nums2) {
        unordered_map hash;
        vector result;
        for(auto val: nums1) hash[val] = true;
        for(auto val: nums2) 
            if(hash.count(val))
            {
                result.push_back(val);
                hash.erase(val);
            }
        return result;
    }
};

python

class Solution(object):
    def intersection(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        ans = []
        dic = {}
        for val in nums1:
            dic[val] = True
        for val in nums2:
            if dic.has_key(val):
                del dic[val]
                ans.append(val)
        return ans

class Solution(object):
    def intersection(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        return list(set(nums1) & set(nums2))