Create 677.MapSumPairs.py

Author: YuriSpiridonov

Medium/677.MapSumPairs.py

@@ -0,0 +1,79 @@
+'''
+    Implement the MapSum class:
+        - MapSum() Initializes the MapSum object.
+        - void insert(String key, int val) Inserts the key-val 
+          pair into the map. If the key already existed, the 
+          original key-value pair will be overridden to the 
+          new one.
+        - int sum(string prefix) Returns the sum of all the 
+          pairs' value whose key starts with the prefix.
+
+    Example:
+    Input
+            ["MapSum", "insert", "sum", "insert", "sum"]
+            [[], ["apple", 3], ["ap"], ["app", 2], ["ap"]]
+    Output
+            [null, null, 3, null, 5]
+    Explanation
+                MapSum mapSum = new MapSum();
+                mapSum.insert("apple", 3);  
+                mapSum.sum("ap");           // return 3 
+                                            // (apple = 3)
+                mapSum.insert("app", 2);    
+                mapSum.sum("ap");           // return 5 
+                                            // (apple + app = 3 + 2 = 5)
+
+    Constraints:
+        - 1 <= key.length, prefix.length <= 50
+        - key and prefix consist of only lowercase English 
+          letters.
+        - 1 <= val <= 1000
+        - At most 50 calls will be made to insert and sum.
+'''
+#Difficulty: Medium
+#34 / 34 test cases passed.
+#Runtime: 28 ms
+#Memory Usage: 14.3 MB
+
+#Runtime: 28 ms, faster than 86.01% of Python3 online submissions for Map Sum Pairs.
+#Memory Usage: 14.3 MB, less than 34.50% of Python3 online submissions for Map Sum Pairs.
+
+class MapSum:
+
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.letters = [None] * 26
+        self.value = 0
+
+    def insert(self, key: str, val: int) -> None:
+        current = self
+        i = 0
+        while i < len(key):
+            index = ord(key[i]) - 97
+            if not current.letters[index]:
+                current.letters[index] = MapSum()
+            current = current.letters[index]
+            i += 1
+        current.value = val
+
+    def sum(self, prefix: str) -> int:
+        current = self
+        result = 0
+        queue = []
+        queue.extend(list(prefix))
+        while queue and current:  
+            current = current.letters[ord(queue.pop(0)) - 97]
+        queue.append(current)
+        while queue and current:
+            current = queue.pop(0)
+            queue.extend([letter for letter in current.letters if letter])
+            result += current.value
+        return result
+
+
+# Your MapSum object will be instantiated and called as such:
+# obj = MapSum()
+# obj.insert(key,val)
+# param_2 = obj.sum(prefix)