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At the moment my solution is to iterate through the map to solve this.
I see there is a upper_bound method which can make this loop faster, but is there a quicker or more succinct way?
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To check for the existence of a particular key in the map, the standard solution is to use the public member function find() of the ordered or the unordered map container, which returns an iterator to the key-value pair if the specified key is found, or iterator to the end of the container if the specified key is not ...
map::size() function is an inbuilt function in C++ STL, which is defined in header file. size() is used to check the size of the map container. This function gives size or we can say gives us the number of elements in the map container associated.
Time complexity: k*log(n) where n is size of map, k is no. of elements inserted.
The end:
m.rbegin(); Maps (and sets) are sorted, so the first element is the smallest, and the last element is the largest. By default maps use std::less, but you can switch the comparer and this would of course change the position of the largest element. (For example, using std::greater would place it at begin().
Keep in mind rbegin returns an iterator. To get the actual key, use m.rbegin()->first. You might wrap it up into a function for clarity, though I"m not sure if it's worth it:
template <typename T> inline const typename T::key_type& last_key(const T& pMap) { return pMap.rbegin()->first; } typedef std::map</* types */> map_type; map_type myMap; // populate map_type::key_type k = last_key(myMap); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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