349. Intersection of Two Arrays

题目：

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.

链接：

https://leetcode.com/problems/intersection-of-two-arrays/?tab=Description

3/12/2017

需要熟悉Java各种数据结构的函数，比如HashSet可以直接一步到Integer Array，但是不可以到int[]，除非手动遍历

public class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        HashSet<Integer> h1 = new HashSet<Integer>();
        HashSet<Integer> h2 = new HashSet<Integer>();

        for (int c: nums1) {
            h1.add(c);
        }
        for (int c: nums2) {
            if (h1.contains(c)) h2.add(c);
        }
        int ret[] = new int[h2.size()];
        int i = 0;
        for (Integer e: h2) {
            ret[i++] = e;
        }
        return ret;
    }
}