LeetCode 2235: Add Two Integers (Direct Arithmetic Return)

Today we solve LeetCode 2235 - Add Two Integers. It looks simple, but it is a clean baseline for function signature, constraints awareness, and constant-time implementation.

Source: https://leetcode.com/problems/add-two-integers/

English

Problem Summary

Given two integers num1 and num2, return their sum.

Key Insight

The required output is exactly the arithmetic addition num1 + num2. No loops, no extra data structure, no edge-case branching beyond language integer handling.

Algorithm

1) Receive num1 and num2.
2) Compute num1 + num2.
3) Return the result.

Complexity Analysis

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

Common Pitfalls

- Overengineering a trivial problem with unnecessary conditions or loops.
- Forgetting to return the computed value.
- In strongly typed languages, using a narrower integer type than constraints require.

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

class Solution {
    public int sum(int num1, int num2) {
        return num1 + num2;
    }
}

func sum(num1 int, num2 int) int {
    return num1 + num2
}

class Solution {
public:
    int sum(int num1, int num2) {
        return num1 + num2;
    }
};

class Solution:
    def sum(self, num1: int, num2: int) -> int:
        return num1 + num2

/**
 * @param {number} num1
 * @param {number} num2
 * @return {number}
 */
var sum = function(num1, num2) {
  return num1 + num2;
};

中文

题目概述

给定两个整数 num1 和 num2，返回它们的和。

核心思路

题目目标非常直接：结果就是 num1 + num2。不需要循环、不需要额外数据结构。

算法步骤

1）读入 num1、num2。
2）计算两者之和。
3）返回结果。

复杂度分析

时间复杂度：O(1)。
空间复杂度：O(1)。

常见陷阱

- 把简单题复杂化，加入无意义分支。
- 计算后忘记返回。
- 在强类型语言中使用不合适的整数类型。

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

class Solution {
    public int sum(int num1, int num2) {
        return num1 + num2;
    }
}

func sum(num1 int, num2 int) int {
    return num1 + num2
}

class Solution {
public:
    int sum(int num1, int num2) {
        return num1 + num2;
    }
};

class Solution:
    def sum(self, num1: int, num2: int) -> int:
        return num1 + num2

/**
 * @param {number} num1
 * @param {number} num2
 * @return {number}
 */
var sum = function(num1, num2) {
  return num1 + num2;
};