[chapse57] Week 1

contains-duplicate/chapse57.py

@@ -0,0 +1,11 @@
+class Solution(object):
+    def containsDuplicate(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: bool
+        """
+        for i in range(len(nums)):
+            for j in range(i+1,len(nums)):
+                if nums[i] == nums[j]:
+                    return True
+        return False

top-k-frequent-elements/chapse57.py

@@ -0,0 +1,22 @@
+class Solution(object):
+    def topKFrequent(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: List[int]
+        """
+        count = {}
+        for n in nums:
+            if n in count:
+                count[n] +=1
+            else:
+                count[n] =1      
+                # count.items()를 횟수 큰 순으로 정렬
+        freq = sorted(count.items(), key=lambda x: x[1], reverse=True)
+
+        result = []
+        for x in freq[:k]:
+            result.append(x[0])
+        return result
+
+

two-sum/chapse57.py

@@ -0,0 +1,14 @@
+class Solution(object):
+    def twoSum(self, nums, target):
+        """
+        :type nums: List[int]
+        :type target: int
+        :rtype: List[int]
+        """
+        seen = {}
+        for i in range(len(nums)):
+            if (target - nums[i]) in seen:
+                return [seen[target - nums[i]],i]   
+            seen[nums[i]] =i
+
+