[leetCode刷题笔记]2017.03.25

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;
}
}