[LeetCode] 677. Map Sum Pairs

- Problem

677. Map Sum Pairs

Design a map that allows you to do the following:

• Maps a string key to a given value.
• Returns the sum of the values that have a key with a prefix equal to a given string.

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 1:

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.

- 내 풀이

class TrieNode:
    def __init__(self):
        self.children = dict()
        self.val = 0
        
class MapSum:

    def __init__(self):
        self.root = TrieNode()

    def insert(self, key: str, val: int) -> None:
        curr = self.root
        
        for k in key:
            if k not in curr.children:
                curr.children[k] = TrieNode()
            curr = curr.children[k]
        
        curr.val = val

    def sum(self, prefix: str) -> int:
        answer = 0
        curr = self.root
        
        for c in prefix:
            if c not in curr.children:
                return 0
            curr = curr.children[c]
        
        q = collections.deque([curr])
        
        while q:
            curr = q.popleft()
            answer += curr.val
            
            for i in curr.children.values():
                q.append(i)
        
        return answer


# Your MapSum object will be instantiated and called as such:
# obj = MapSum()
# obj.insert(key,val)
# param_2 = obj.sum(prefix)

- 결과