[英]What's the time complexity of iterating through a std::set/std::map?
What's the time complexity of iterating through a std::set
/ std::multiset
/ std::map
/ std::multimap
? 迭代
std::set
/ std::multiset
/ std::map
/ std::multimap
的时间复杂度是多少? I believe that it is linear in the size of the set/map, but not so sure. 我相信它在集合/地图的大小上是线性的,但不是那么肯定。 Is it specified in the language standard?
是否在语言标准中指定?
In the draft C++11 standard N3337 the answer can be found in § 24.2.1 paragraph 8: 在C ++ 11标准N3337草案中 ,答案可以在第24.2.1段第8段中找到:
All the categories of iterators require only those functions that are realizable for a given category in constant time (amortized).
所有迭代器类别仅需要在恒定时间内(摊销)可以为给定类别实现的那些函数。
Since each operation on an iterator must be constant time, iterating through n
elements must be O(n)
. 由于迭代器上的每个操作必须是恒定时间,因此遍历
n
元素必须是O(n)
。
I believe that it is linear in the size of the set/map, but not so sure.
我相信它在集合/地图的大小上是线性的,但不是那么肯定。
That is correct. 那是正确的。 Iterating through an entire set or map is amortized
O(N)
迭代整个集合或映射是摊销
O(N)
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