C# 循环遍历字典并对键的值求和

Question

我有一个 Dictionary<string, decimal?> ，我希望能够通过不同的字符串对小数求和。所以说我在字典中有以下输入，

“1”, 20.00“1”，35.00“2”，10.00"3", 15.00"3", 30.00

我想将以下输出到新词典

“1”, 55.00“2”，10.00"3", 45.00

我猜应该是这样的

foreach(var item in dictionary)
{
newDictionary.Add(not sure what would go here, maybe some sort of linq query for distinct and sum?);
}

Answer 1

假设键值对列表与其他答案相同:

var myList = New List<KeyValuePair<string, decimal?>> {
    new KeyValuePair<string, decimal?>("1", (decimal)10.00),
    new KeyValuePair<string, decimal?>("1", (decimal)15.00),
    new KeyValuePair<string, decimal?>("2", (decimal)20.00),
    new KeyValuePair<string, decimal?>("3", (decimal)30.50),
    new KeyValuePair<string, decimal?>("3", (decimal)17.500)
};

var myResults = myList.GroupBy(p => p.Key)
                      .ToDictionary(g => g.Key, g=>g.Sum(p=>p.Value))