Intersection of Two Arrays II

Intersection of Two Arrays II

Description

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

Note
- Each element in the result should appear as many times as it shows in both arrays.
- The result can be in any order.

Example 1:

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

Tags: Array、Sort

解读题意

给出两个数组，找出它们的交集。结果允许重复；结果无序排序

思路1

1. 先对两个数组进行排序
2. 定义两个指针i和j，分别来控制nums1和nums2。比较nums[i]和nums[j]，若nums[i] > nums[j]则j+1,若nums[i] < nums[j]则i+1,否则将nums[i]添加到结果集中，并且i和j均+1

class Solution {

   public int[] intersect(int[] nums1, int[] nums2) {

        if (nums1 == null || nums2 == null ||
                nums1.length == 0 || nums2.length == 0)
            return new int[]{};

        Arrays.sort(nums1);
        Arrays.sort(nums2);

        int i = 0, j = 0;
        List list = new ArrayList<>();
        while (i < nums1.length && j < nums2.length) {

            if (nums1[i] < nums2[j])
                i++;
            else if (nums1[i] > nums2[j])
                j++;
            else {
                list.add(nums1[i]);
                i++;
                j++;
            }
        }

        int[] result = new int[list.size()];
        int index = 0;
        for (int x : list) {
            result[index++] = x;
        }

        return result;
   }
}

time complexity:O(n)

leetCode汇总：https://blog.csdn.net/qingtian_1993/article/details/80588941

项目源码，欢迎star：https://github.com/mcrwayfun/java-leet-code