Package g0601_0700.s0677_map_sum_pairs

Class MapSum

java.lang.Object
g0601_0700.s0677_map_sum_pairs.MapSum
public class MapSum extends Object
677 - Map Sum Pairs.

Medium

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.

  • Constructor Details

    • MapSum

      public MapSum()

  • Method Details

    • insert

      public void insert(String key, int val)

    • sum

      public int sum(String prefix)