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Author: assassint2017

Combinations/Combinations.py

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+# 第一种思路
+# 740ms 45.65%
+class Solution:
+    def combine(self, n, k):
+        """
+        :type n: int
+        :type k: int
+        :rtype: List[List[int]]
+        """
+        def mycombine(num_list, temp_list):
+            if len(temp_list) == k - 1:
+                for num in num_list:
+                    res_list.append(temp_list + [num])
+            for index in range(len(num_list)):
+                mycombine(num_list[index + 1:], temp_list + [num_list[index]])
+            
+        res_list = []
+        mycombine(list(range(1, n + 1)), [])
+        return res_list
+
+# 第二种思路，讨论区一个大神给出的思路，但是并没有看懂
+# 172ms 76.24%
+class Solution:
+    def combine(self, n, k):
+        """
+        :type n: int
+        :type k: int
+        :rtype: List[List[int]]
+        """ 
+        if k == 0:
+            return [[]]
+        return [pre + [i] for i in range(k, n+1) for pre in self.combine(i-1, k-1)]