JavaArithmetic/src/LeetCode/Leetcode350.java at master · git-jhy/JavaArithmetic · GitHub

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package LeetCode;

import java.util.ArrayList;

import java.util.TreeMap;

public class Leetcode350 {

// https://leetcode.com/problems/intersection-of-two-arrays-ii/description/

// 时间复杂度: O(nlogn)

// 空间复杂度: O(n)

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

TreeMap<Integer, Integer> record = new TreeMap<Integer, Integer>();

// 遍历nums1，放入map中，value是频率

for (int num : nums1)

if (!record.containsKey(num))

record.put(num, 1);

else

record.put(num, record.get(num) + 1);

ArrayList<Integer> result = new ArrayList<Integer>();

for (int num : nums2)

if (record.containsKey(num) && record.get(num) > 0) {

result.add(num);

record.put(num, record.get(num) - 1);

}

int[] ret = new int[result.size()];

int index = 0;

for (Integer num : result)

ret[index++] = num;

return ret;

}