Package g0601_0700.s0677_map_sum_pairs

Class MapSum

java.lang.Object
g0601_0700.s0677_map_sum_pairs.MapSum
public class MapSum extends java.lang.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 Summary

    Constructors
    Constructor
    Description
    MapSum()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    insert(java.lang.String key, int val)
     
    int
    sum(java.lang.String prefix)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • MapSum

      public MapSum()

  • Method Details

    • insert

      public void insert(java.lang.String key, int val)

    • sum

      public int sum(java.lang.String prefix)