adding solution for lruCache in python (codedecks-in#113)

Author: sachinnegi

Python/LRUCache.py

@@ -0,0 +1,69 @@
+class ListNode(object):
+ def __init__(self,key,val):
+ self.key = key
+ self.value = val
+ self.next = None
+ self.prev = None
+
+class LRUCache:
+
+ def __init__(self, capacity: int):
+ self.cap = capacity
+ self.dic = {}
+ self.head = ListNode(-1,-1)
+ self.tail = ListNode(-1,-1)
+ self.head.next = self.tail
+ self.tail.prev = self.head
+ 
+
+ def get(self, key: int) -> int:
+ if key in self.dic:
+ node = self.dic[key]
+ self.remove(node)
+ self.add(node)
+ return node.value
+ return -1
+
+ def put(self, key: int, value: int) -> None:
+ 
+ if key in self.dic:
+ node = self.dic[key]
+ self.remove(node)
+ del self.dic[node.key]
+ if len(self.dic)>=self.cap:
+ node = self.head.next
+ self.remove(node)
+ del self.dic[node.key]
+ 
+ node = ListNode(key,value)
+ self.dic[key] = node
+ self.add(node)
+ # self.show(self.head)
+ 
+ 
+ 
+ def remove(self,node):
+ prevNode = node.prev
+ prevNode.next = node.next
+ node.next.prev = prevNode
+ 
+ def add(self,node):
+ tailprev = self.tail.prev
+ tailprev.next = node
+ node.prev = tailprev
+ node.next = self.tail
+ self.tail.prev = node
+ # self.show(self.head)
+ 
+ def show(self,head):
+ while head:
+ print(head.value,end=" ")
+ head = head.next
+ print()
+ 
+
+
+# Your LRUCache object will be instantiated and called as such:
+# obj = LRUCache(capacity)
+# param_1 = obj.get(key)
+# obj.put(key,value)

README.md

@@ -157,7 +157,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 109 | [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) | [Java](./Java/convert-sorted-list-to-binary-search-tree.java) | _O(n)_ | _O(n)_ | Medium | LinkedList | |
 | 141 | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/) | [Java](./Java/linked-list-cycle.java) | _O(n)_ | _O(1)_ | Easy | Slow-Fast Pointers | |
 | 142 | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/) | [Java](./Java/linked-list-cycle-ii.java) <br> [C++](./C++/Linked-List-Cycle-II.cpp) | _O(n)_ | _O(1)_ | Medium | Slow-Fast Pointers | |
-| 146 | [LRU Cache](https://leetcode.com/problems/lru-cache/) | [C++](./C++/LRU-Cache.cpp)   | _O(1)_ | _O(k)_ | Medium | Hash Map | |
+| 146 | [LRU Cache](https://leetcode.com/problems/lru-cache/) | [C++](./C++/LRU-Cache.cpp) <br> [Python](./Python/LRUCache.py) | _O(1)_ | _O(k)_ | Medium | Hash Map | |
 | 186 | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/) | [Java](./Java/middle-of-the-linked-list.java) | _O(n)_ | _O(1)_ | Easy | Two pointers | |
 | 23 | [Merge K sorted lists](https://leetcode.com/problems/merge-k-sorted-lists/) | [C++](./C++/merge-k-sorted-lists.cpp) | _O(nlogn)_ | _O(n)_ | Hard | sorting and append | |
 
@@ -204,7 +204,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 
 | # | Title | Solution | Time | Space | Difficulty | Tag | Note |
 | ---- | --------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- | ----------- | ----------- | ---------- | ---------------------------------------------- | ---- |
-| 094 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) | [Java](./Java/binary-tree-inorder-traversal.java) </br> [Python](./Python/Iterative-Inorder-tree-traversal) | _O(n)_ | _O(logn)_ | Medium | Binary Tree, Stack, HashTable | |
+| 094 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) | [Java](./Java/binary-tree-inorder-traversal.java) <br> [Python](./Python/Iterative-Inorder-tree-traversal) | _O(n)_ | _O(logn)_ | Medium | Binary Tree, Stack, HashTable | |
 | 100 | [Same Tree](https://leetcode.com/problems/same-tree/) | [Python](./Python/100.SymmetricTree.py) | _O(n)_ | _O(n)_ | Easy | Tree, Depth-first Search | |
 | 101 | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/) | [Java](./Java/symmetric-tree.java)<br>[Python](./Python/101.SymmetricTree.py) | _O(n)_ | _O(n)_ | Easy | Tree, Breadth-first Search, Depth-first Search | |
 | 144 | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/) | [Java](./Java/binary-tree-preorder-traversal.java) | _O(n)_ | _O(logn)_ | Medium | Binary Tree, Stack | |