这篇文章整理了algorithm.

#include <algorithm>

Empirical Observation

#

std::unique

template <class ForwardIterator>
ForwardIterator unique(ForwardIterator first, ForwardIterator last);

template <class ForwardIterator, class BinaryPredicate>
ForwardIterator unique(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);

1. In-Place Operation: std::unique does not resize the container or physically remove elements. It simply shifts the unique elements to the front.
2. Range Assumption: The range should be sorted if you want to remove all duplicates. Otherwise, only consecutive duplicates are removed.
3. Reclaim Space: If used on a container like std::vector, you need to call erase to remove the redundant elements physically.

an example

#include <iostream>
#include <vector>
#include <algorithm>

bool almost_equal(double a, double b) {
    return std::abs(a - b) < 0.1;
}

int main() {
    std::vector<double> vec = {1.01, 1.02, 2.0, 2.05, 3.0};

    // Remove consecutive "almost equal" duplicates
    auto new_end = std::unique(vec.begin(), vec.end(), almost_equal);

    vec.erase(new_end, vec.end());

    for (double num : vec) {
        std::cout << num << " ";
    }

    return 0;
}