std::less by std::get (tools/less_by_get.hpp)

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• Last update: 2022-03-20 20:07:20+09:00
• Include: #include "tools/less_by_get.hpp"

It compares two values by std::get.

Usage

std::vector<std::tuple<int, int, int>> a;
std::sort(a.begin(), a.end(), tools::less_by_get<2>());

License

• CC0

Author

• anqooqie

Constructor

template <std::size_t I>
tools::less_by_get<I> comp();

It creates a comparator.

Constraints

• None

Time Complexity

• $O(1)$

operator()

template <typename T>
bool comp.operator()(T x, T y);

It returns true if std::get<I>(x) < std::get<I>(y). Otherwise, it returns false.

Constraints

• None

Time Complexity

• $O(1)$

Required by

• Mo's algorithm (tools/mo.hpp)
• 0-1 knapsack problem (tools/zero_one_knapsack.hpp)

Verified with

• tests/avl_tree/binary_search.test.cpp
• tests/mo.test.cpp
• tests/zero_one_knapsack/solve_by_dp_maximizing_value.test.cpp
• tests/zero_one_knapsack/solve_by_dp_minimizing_weight.test.cpp
• tests/zero_one_knapsack/solve_by_meet_in_the_middle.test.cpp

Code

#ifndef TOOLS_LESS_BY_GET_HPP
#define TOOLS_LESS_BY_GET_HPP

#include <cstddef>
#include <tuple>

namespace tools {

  template <::std::size_t I>
  struct less_by_get {
    template <class T>
    bool operator()(const T& x, const T& y) const {
      return ::std::get<I>(x) < ::std::get<I>(y);
    }
  };
}

#endif

#line 1 "tools/less_by_get.hpp"



#include <cstddef>
#include <tuple>

namespace tools {

  template <::std::size_t I>
  struct less_by_get {
    template <class T>
    bool operator()(const T& x, const T& y) const {
      return ::std::get<I>(x) < ::std::get<I>(y);
    }
  };
}

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