2018-09-15 11:29:17 +00:00
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# [349. Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/description/)
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# 思路
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题目欲求两个数组的交集，注意集合里元素都是唯一的。可以考虑将两个数组进行排序，再用两个指针分别遍历两个有序数组，合理更新指针即可获取两个数组的重复元素。
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为了没有重复的元素，可以设置一个pre来记录上一个相同的元素是什么。
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时间复杂度O(nlogn)
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当然也可以用map来查看是否有相同元素。
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# C++
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2019-09-13 15:08:41 +00:00
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```C++
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2018-09-15 11:29:17 +00:00
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class Solution {
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public:
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vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {
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sort(nums1.begin(), nums1.end());
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sort(nums2.begin(), nums2.end());
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vector<int>res;
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int p1 = 0, p2 = 0, pre;
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while(p1 < nums1.size() && p2 < nums2.size()){
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if(nums1[p1] < nums2[p2]) p1++;
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else if(nums1[p1] > nums2[p2]) p2++;
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else{
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if(res.empty() || pre != nums1[p1]){
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res.push_back(nums1[p1]);
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pre = nums1[p1];
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}
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p1++;
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p2++;
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}
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}
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return res;
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}
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};
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```
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