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]
题意：
如题
Solution1： HashSet
1. Scan nums1, put items in nums1 to set1
2. Scan nums2, check each item is contained in set1
注意： HashSet.contains() -> O(1)
code
1 class Solution { 2 public int[] intersection(int[] nums1, int[] nums2) { 3 HashSet <Integer> set1 = new HashSet<>(); 4 HashSet <Integer> resSet = new HashSet<>(); 5 6 for (int i = 0; i < nums1.length; i ++) { 7 set1.add(nums1[i]); 8 } 9 for (int i = 0; i < nums2.length; i ++) { 10 if (set1.contains(nums2[i])) { 11 resSet.add(nums2[i]); 12 } 13 } 14 // resSet -> int[]res 15 int [] res = new int[resSet.size()]; 16 int index = 0; 17 for (int num : resSet) { 18 res[index++] = num; 19 } 20 return res; 21 } 22 }
转载于:https://www.cnblogs.com/liuliu5151/p/9810411.html
