55 lines
1.8 KiB
C++
55 lines
1.8 KiB
C++
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#include <cassert>
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#include <iostream>
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#include <iterator>
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#include <vector>
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template <typename InputIt, typename OutputIt, typename Pred>
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std::pair<InputIt, OutputIt> copy_while(InputIt first, InputIt last,
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OutputIt out, Pred p) {
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// Iterate through the input range
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while (first != last && p(*first)) {
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*out = *first; // Copy the value to the output
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++first; // Move to the next input element
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++out; // Move to the next output element
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}
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// Return the pair of iterators
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return {first, out};
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}
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std::vector<int> take_while_sum_less_than(std::vector<int> &invec, int n) {
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std::vector<int> out;
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int sum = 0;
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copy_while(invec.begin(), invec.end(), std::back_inserter(out),
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[&](int &x) -> bool { return (sum += x) < n; });
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return out;
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}
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int main() {
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// Sample data
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std::vector<int> input = {1, 2, 3, 6,
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7, 8}; // We will stop copying when we encounter 6
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std::vector<int> output;
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// Define the predicate: copy while the value is <= 5
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auto pred = [](int n) { return n <= 5; };
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// Call copy_while with the test data
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auto [new_first, new_out] = copy_while(input.begin(), input.end(),
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std::back_inserter(output), pred);
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// Assert that the copied elements are correct (only the first three
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// elements)
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std::vector<int> test = std::vector<int>{1, 2, 3};
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assert(output == test);
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// Assert that the iterator returned points to the element that did not
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// match the predicate (6)
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assert(*new_first == 6);
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std::vector<int> v{1, 2, 3};
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auto w = take_while_sum_less_than(v, 10);
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std::cout << "Hello" << std::endl;
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std::for_each(w.begin(), w.end(),
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[](int &a) { std::cout << a << " " << std::endl; });
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}
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