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+# Step1
+自力で解く
+```python
+class Solution:
+    def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
+        intersection_nums =[]
+        for num1 in nums1:
+            if num1 not in intersection_nums and num1 in nums2:
+                intersection_nums.append(num1)
+        return intersection_nums
+```
+ひとまずfor文で回した．辞書を使えばもっと計算効率上がるかも
+
+# Step2
+調べてみる．setという組み込み関数があるらしい
+https://qiita.com/KueharX/items/a8cc7831fc430e9340ca
+setはuniqueな値を辞書型で返すので，list()で括る
+```python
+class Solution:
+    def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
+        intersected_nums = list(set(nums1) & set(nums2))
+        return intersected_nums
+```