Chmin Chmax
(utilities/chmin_chmax.hpp)

• View this file on GitHub
• Last update: 2026-06-16 01:13:59+09:00
• Include: #include "utilities/chmin_chmax.hpp"

Overview

Small update helpers for dynamic programming and relaxation code. Each function updates the first argument only when the new value improves it, and returns whether the update happened.

Functions

Function	Description	Complexity
bool chmin(T& a, const U& b)	Sets a = b if b < a.	$O(1)$
bool chmax(T& a, const U& b)	Sets a = b if a < b.	$O(1)$

Example

#include "utilities/chmin_chmax.hpp"
#include <iostream>

int main() {
    int best = 100;
    bool updated = m1une::utilities::chmin(best, 42);
    std::cout << updated << " " << best << "\n";
}

Verified with

• verify/utilities/extra_utilities.test.cpp

Code

#ifndef M1UNE_CHMIN_CHMAX_HPP
#define M1UNE_CHMIN_CHMAX_HPP 1

namespace m1une {
namespace utilities {

template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

}  // namespace utilities
}  // namespace m1une

#endif  // M1UNE_CHMIN_CHMAX_HPP

#line 1 "utilities/chmin_chmax.hpp"



namespace m1une {
namespace utilities {

template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

}  // namespace utilities
}  // namespace m1une

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