LeetCode 2469: Convert the Temperature (Direct Formula Conversion)

Today we solve LeetCode 2469 - Convert the Temperature.

Source: https://leetcode.com/problems/convert-the-temperature/

English

Problem Summary

Given a Celsius value celsius, return an array [kelvin, fahrenheit] where:

kelvin = celsius + 273.15
fahrenheit = celsius * 1.80 + 32.00

Key Insight

This is a direct formula mapping problem. No loops, no extra structures, and no branching logic are required.

Brute Force and Limitations

There is no meaningful brute-force alternative. The optimal approach is immediate calculation with the two given formulas.

Optimal Formula Steps

1) Read celsius as floating point.
2) Compute kelvin = celsius + 273.15.
3) Compute fahrenheit = celsius * 1.80 + 32.00.
4) Return the two values in the required order.

Complexity Analysis

Time: O(1).
Space: O(1).

Common Pitfalls

- Returning values in wrong order (must be Kelvin first).
- Using integer math and losing decimal precision.
- Mistyping constants (273.15, 1.80, 32.00).

Reference Implementations (Java / Go / C++ / Python / JavaScript)

class Solution {
    public double[] convertTemperature(double celsius) {
        double kelvin = celsius + 273.15;
        double fahrenheit = celsius * 1.80 + 32.00;
        return new double[]{kelvin, fahrenheit};
    }
}

func convertTemperature(celsius float64) []float64 {
    kelvin := celsius + 273.15
    fahrenheit := celsius*1.80 + 32.00
    return []float64{kelvin, fahrenheit}
}

class Solution {
public:
    vector<double> convertTemperature(double celsius) {
        double kelvin = celsius + 273.15;
        double fahrenheit = celsius * 1.80 + 32.00;
        return {kelvin, fahrenheit};
    }
};

class Solution:
    def convertTemperature(self, celsius: float) -> list[float]:
        kelvin = celsius + 273.15
        fahrenheit = celsius * 1.80 + 32.00
        return [kelvin, fahrenheit]

var convertTemperature = function(celsius) {
  const kelvin = celsius + 273.15;
  const fahrenheit = celsius * 1.80 + 32.00;
  return [kelvin, fahrenheit];
};

中文

题目概述

给定摄氏温度 celsius，返回数组 [kelvin, fahrenheit]，其中：

kelvin = celsius + 273.15
fahrenheit = celsius * 1.80 + 32.00

核心思路

这是纯公式转换题。直接按定义计算两个结果并按顺序返回即可。

暴力解法与不足

本题没有必要设计枚举或模拟流程，最优解就是常数时间公式计算。

最优解步骤

1）读取浮点输入 celsius。
2）计算 kelvin = celsius + 273.15。
3）计算 fahrenheit = celsius * 1.80 + 32.00。
4）按 [kelvin, fahrenheit] 顺序返回。

复杂度分析

时间复杂度：O(1)。
空间复杂度：O(1)。

常见陷阱

- 返回顺序写反。
- 使用整型导致小数精度丢失。
- 常量写错（273.15、1.80、32.00）。

多语言参考实现（Java / Go / C++ / Python / JavaScript）

class Solution {
    public double[] convertTemperature(double celsius) {
        double kelvin = celsius + 273.15;
        double fahrenheit = celsius * 1.80 + 32.00;
        return new double[]{kelvin, fahrenheit};
    }
}

func convertTemperature(celsius float64) []float64 {
    kelvin := celsius + 273.15
    fahrenheit := celsius*1.80 + 32.00
    return []float64{kelvin, fahrenheit}
}

class Solution {
public:
    vector<double> convertTemperature(double celsius) {
        double kelvin = celsius + 273.15;
        double fahrenheit = celsius * 1.80 + 32.00;
        return {kelvin, fahrenheit};
    }
};

class Solution:
    def convertTemperature(self, celsius: float) -> list[float]:
        kelvin = celsius + 273.15
        fahrenheit = celsius * 1.80 + 32.00
        return [kelvin, fahrenheit]

var convertTemperature = function(celsius) {
  const kelvin = celsius + 273.15;
  const fahrenheit = celsius * 1.80 + 32.00;
  return [kelvin, fahrenheit];
};