chmax function (tools/chmax.hpp)

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• Last update: 2025-01-25 08:45:50+09:00
• Include: #include "tools/chmax.hpp"

template <typename M, typename N>
bool chmax(M& lhs, N rhs);

It runs lhs = std::max(lhs, rhs);. It returns true if lhs has been updated. Otherwise, it returns false.

Constraints

• None

Time Complexity

• $O(1)$

License

• CC0

Author

• anqooqie

Required by

• Largest rectangle in histogram (tools/largest_rectangle_in_histogram.hpp)
• Longest common substring (tools/longest_common_substring.hpp)
• Wrapper of atcoder::suffix_array and atcoder::lcp_array (tools/suffix_array.hpp)
• 0-1 knapsack problem (tools/zero_one_knapsack.hpp)

Verified with

• tests/cartesian_tree/interval.test.cpp
• tests/largest_rectangle_in_histogram.test.cpp
• tests/longest_common_substring.test.cpp
• tests/next_matching.test.cpp
• tests/rolling_hash.test.cpp
• tests/suffix_array.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_CHMAX_HPP
#define TOOLS_CHMAX_HPP

#include <type_traits>
#include <utility>

namespace tools {

  template <typename M, typename N>
  bool chmax(M& lhs, const N& rhs) {
    bool updated;
    if constexpr (::std::is_integral_v<M> && ::std::is_integral_v<N>) {
      updated = ::std::cmp_less(lhs, rhs);
    } else {
      updated = lhs < rhs;
    }
    if (updated) lhs = rhs;
    return updated;
  }
}

#endif

#line 1 "tools/chmax.hpp"



#include <type_traits>
#include <utility>

namespace tools {

  template <typename M, typename N>
  bool chmax(M& lhs, const N& rhs) {
    bool updated;
    if constexpr (::std::is_integral_v<M> && ::std::is_integral_v<N>) {
      updated = ::std::cmp_less(lhs, rhs);
    } else {
      updated = lhs < rhs;
    }
    if (updated) lhs = rhs;
    return updated;
  }
}

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