LeetCode //C - 260. Single Number III

260. Single Number III

Given an integer array nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. You can return the answer in any order.

You must write an algorithm that runs in linear runtime complexity and uses only constant extra space.

Example 1:

Input: nums = [1,2,1,3,2,5]
Output: [3,5]
Explanation: [5, 3] is also a valid answer.

Example 2:

Input: nums = [-1,0]
Output: [-1,0]

Example 3:

Input: nums = [0,1]
Output: [1,0]

Constraints:
  • 2 < = n u m s . l e n g t h < = 3 ∗ 1 0 4 2 <= nums.length <= 3 * 10^4 2<=nums.length<=3∗104
  • − 2 31 < = n u m s [ i ] < = 2 31 − 1 -2^{31} <= nums[i] <= 2^{31} - 1 −231<=nums[i]<=231−1
  • Each integer in nums will appear twice, only two integers will appear once.

From: LeetCode

Link: 260. Single Number III


Solution:

Ideas:

Use of Unsigned Type:

  • By casting xor_result to an unsigned int, we avoid the undefined behavior associated with negating the most negative integer.
  • The expression -(unsigned int)xor_result safely computes the two's complement for the unsigned value.
  • set_bit now correctly isolates the rightmost set bit without causing any runtime errors.
Code:
c 复制代码
/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* singleNumber(int* nums, int numsSize, int* returnSize) {
    int xor_result = 0;
    for (int i = 0; i < numsSize; i++) {
        xor_result ^= nums[i];
    }

    // Cast to unsigned int for safe bit manipulation
    unsigned int set_bit = (unsigned int)xor_result & (-(unsigned int)xor_result);

    int num1 = 0, num2 = 0;
    for (int i = 0; i < numsSize; i++) {
        if ((nums[i] & set_bit) != 0) {
            num1 ^= nums[i];
        } else {
            num2 ^= nums[i];
        }
    }

    int* result = (int*)malloc(2 * sizeof(int));
    result[0] = num1;
    result[1] = num2;
    *returnSize = 2;

    return result;
}
相关推荐
诸葛务农21 分钟前
光电对抗:多模/复合制导中算法和软件平台
算法
Starshime28 分钟前
【C语言】变量和常量
c语言·开发语言
晨非辰31 分钟前
#C语言——刷题攻略:牛客编程入门训练(十):攻克 循环控制(二),轻松拿捏!
c语言·开发语言·经验分享·学习·visual studio
Swift社区42 分钟前
LeetCode 378 - 有序矩阵中第 K 小的元素
算法·leetcode·矩阵
墨染点香1 小时前
LeetCode 刷题【73. 矩阵置零】
算法·leetcode·矩阵
tqs_123451 小时前
redis zset score的计算
java·算法
_Coin_-1 小时前
算法训练营DAY60 第十一章:图论part11
算法·图论
林木辛1 小时前
LeetCode热题 438.找到字符中所有字母异位词 (滑动窗口)
算法·leetcode
和鲸社区1 小时前
四大经典案例,入门AI算法应用,含分类、回归与特征工程|2025人工智能实训季初阶赛
人工智能·python·深度学习·算法·机器学习·分类·回归