https://leetcode.com/problems/intersection-of-two-arrays/
Given two arrays, write a function to calculate 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]
description：
Each element in the output must be unique.
We can not consider the order of the output results.
- hashtable
-Ali -Tencent -Baidu -Byte
First traverse the first array, store it in the hashtable, and then traverse the second array. If it exists in the hashtable, push it to ret, then empty the hashtable, and finally return to ret.
-Space for time
Code support: JS, Python
Javascript Code:
/**
* @param {number[]} nums1
* @param {number[]} nums2
* @return {number[]}
*/
var intersection = function (nums1, nums2) {
const visited = {};
const ret = [];
for (let i = 0; i < nums1. length; i++) {
const num = nums1[i];
visited[num] = num;
}
for (let i = 0; i < nums2. length; i++) {
const num = nums2[i];
if (visited[num] ! == undefined) {
ret. push(num);
visited[num] = undefined;
}
}
return ret;
};Python Code:
class Solution:
def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
visited, result = {}, []
for num in nums1:
visited[num] = num
for num in nums2:
if num in visited:
result. append(num)
visited. pop(num)
return result
# Another solution: Use collections in Python to calculate
def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
return set(nums1) & set(nums2)Complexity analysis
-Time complexity:$O(N)$ -Spatial complexity:$O(N)$
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