[leetCode刷题笔记]2017.03.25

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349. Intersection of Two Arrays

用到了set。。。

public class Solution {    public int[] intersection(int[] nums1, int[] nums2) {        Set<Integer> oneSet = new HashSet<Integer>();        Set<Integer> resSet = new HashSet<Integer>();                for (int i : nums1) {            oneSet.add(i);        }        for (int i :nums2) {            if (oneSet.contains(i)) {                resSet.add(i);            }        }        int[] result = new int[resSet.size()];        int j = 0;        for (Integer k : resSet) {            result[j++] = k;         }        return result;    }}

350. Intersection of Two Arrays

用hashMap

public class Solution {    public int[] intersect(int[] nums1, int[] nums2) {        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();        ArrayList<Integer> result = new ArrayList<Integer>();        for(int i = 0; i < nums1.length; i++)        {            if(map.containsKey(nums1[i])) map.put(nums1[i], map.get(nums1[i])+1);            else map.put(nums1[i], 1);        }            for(int i = 0; i < nums2.length; i++)        {            if(map.containsKey(nums2[i]) && map.get(nums2[i]) > 0)            {                result.add(nums2[i]);                map.put(nums2[i], map.get(nums2[i])-1);            }        }           int[] r = new int[result.size()];       for(int i = 0; i < result.size(); i++)       {           r[i] = result.get(i);       }           return r;    }}

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