problem0677

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677. Map Sum Pairs

题目

Implement a MapSum class with insert, and sum methods.

For the method insert, you'll be given a pair of (string, integer). The string represents the key and the integer represents the value. If the key already existed, then the original key-value pair will be overridden to the new one.

For the method sum, you'll be given a string representing the prefix, and you need to return the sum of all the pairs' value whose key starts with the prefix.

Example 1:

Input: insert("apple", 3), Output: Null
Input: sum("ap"), Output: 3
Input: insert("app", 2), Output: Null
Input: sum("ap"), Output: 5

解题思路

见程序注释

Documentation

Index

• type MapSum
  • func Constructor() MapSum
  • func (ms *MapSum) Insert(key string, val int)
  • func (ms *MapSum) Sum(prefix string) int

Types

type MapSum

type MapSum struct {
	// contains filtered or unexported fields
}

MapSum 可以返回　map 中具有相同前缀的　value 之和

func Constructor

func Constructor() MapSum

Constructor 构建了 MapSum

func (*MapSum) Insert

func (ms *MapSum) Insert(key string, val int)

Insert 插入 (key, val)

func (*MapSum) Sum

func (ms *MapSum) Sum(prefix string) int

Sum 返回所有具有 prefix 的 key 的 val 之和