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How to populate vector with one billion random numbers?
I am trying to populate a vector of integers with one billion random number. The only constraint is that there can be no duplicates in the array.
How to populate vector in C + + stack overflow?
You iterate the vector, and in each element you add two more. so it is a never ending loop. the .push_back will add at the end of the vector that element, so size () is always increasing. I would suggest something like this. it will set a random number for each element. I recommend using a vector of struct.
Why do you need to search through the vector?
This is because you need to search through the vector as it grows to see if you have a duplicate, which will go through the vector (on average) (1 + 2 + + 999,999,999) / 2 times over the course of the algorithm.
What happens when you initialize a vector to a specific value?
A vector, once declared, has all its values initialized to zero. Following is an example code to demonstrate the same. What if we wish to initialize the vector to a specific value, say 1 ? For this, we can pass the value along with the size of the vector.
What’s the best way to remove duplicates in a vector?
std::unique only removes duplicate elements if they’re neighbours: you have to sort the vector first before it will work as you intend. std::unique is defined to be stable, so the vector will still be sorted after running unique on it.
What’s the best way to sort vector of pointers?
The standard approach suggested by Nate Kohl, just using vector, sort + unique: doesn’t work for a vector of pointers. Look carefully at this example on cplusplus.com.
How does unique remove duplicates from a container?
Additionally, unique doesn’t actually remove elements from the container. Instead, they are copied to the end, unique returns an iterator pointing to the first such duplicate element, and you are expected to call erase to actually remove the elements.