LeetCode //C - 219. Contains Duplicate II

219. Contains Duplicate II

Given an integer array nums and an integer k , return true if there are two distinct indices i and j in the array such that nums[i] == nums[j] and abs(i - j) <= k .

Example 1:

Input: nums = [1,2,3,1], k = 3
Output: true

Example 2:

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

Example 3:

Input: nums = [1,2,3,1,2,3], k = 2
Output: false

Constraints:

  • 1 < = n u m s . l e n g t h < = 1 0 5 1 <= nums.length <= 10^5 1<=nums.length<=105
  • − 1 0 9 < = n u m s [ i ] < = 1 0 9 -10^9 <= nums[i] <= 10^9 −109<=nums[i]<=109
  • 0 < = k < = 1 0 5 0 <= k <= 10^5 0<=k<=105

From: LeetCode

Link: 219. Contains Duplicate II


Solution:

Ideas:
  1. Structure Definition: A structure Number is defined to store two integers: the value of an element from the nums array and its original index in the array.

  2. Array Initialization: An array numbers of type Number is created and initialized with the values and corresponding indices from the input array nums.

  3. Sorting: The numbers array is sorted by the values using the qsort function. The compare function is used to define the sorting order, which is based on the value field of the structure. After sorting, elements with the same value will be adjacent to each other, and their original indices can still be accessed.

  4. Scanning for Duplicates: The sorted numbers array is then scanned to find adjacent pairs with the same value. If such a pair is found, the original indices are checked to see if the absolute difference between them is less than or equal to k. If this condition is met, the function returns true.

  5. Memory Cleanup: The dynamically allocated memory for the numbers array is freed before exiting the function.

  6. Result: If no such pair is found that meets the condition, the function returns false.

By sorting the numbers and keeping track of the original indices, this approach efficiently checks for duplicates within the specified range k. The sorting ensures that the same values are grouped together, making it easy to check the condition without needing a hash table.

Code:
c 复制代码
typedef struct {
    int value;
    int index;
} Number;

int compare(const void *a, const void *b) {
    return ((Number*)a)->value - ((Number*)b)->value;
}

bool containsNearbyDuplicate(int* nums, int numsSize, int k) {
    if (k == 0 || numsSize <= 1) return false;
    
    Number* numbers = (Number*)malloc(numsSize * sizeof(Number));
    for (int i = 0; i < numsSize; i++) {
        numbers[i].value = nums[i];
        numbers[i].index = i;
    }
    
    qsort(numbers, numsSize, sizeof(Number), compare);
    
    for (int i = 0; i < numsSize - 1; i++) {
        if (numbers[i].value == numbers[i + 1].value && 
            abs(numbers[i].index - numbers[i + 1].index) <= k) {
            free(numbers);
            return true;
        }
    }
    
    free(numbers);
    return false;
}
相关推荐
海洲探索-Hydrovo2 小时前
TTP Aether X 天通透传模块丨国产自主可控大数据双向通讯定位模组
网络·人工智能·科技·算法·信息与通信
2401_841495645 小时前
【计算机视觉】基于复杂环境下的车牌识别
人工智能·python·算法·计算机视觉·去噪·车牌识别·字符识别
Jonkin-Ma5 小时前
每日算法(1)之单链表
算法
奔跑吧邓邓子5 小时前
【C语言实战(8)】C语言循环结构(do-while):解锁编程新境界
c语言·实战·do-while
晚风残5 小时前
【C++ Primer】第六章:函数
开发语言·c++·算法·c++ primer
小莞尔5 小时前
【51单片机】【protues仿真】基于51单片机温度测量系统
c语言·单片机·嵌入式硬件·物联网·51单片机
杨云强5 小时前
离散积分,相同表达式数组和公式
算法
地平线开发者5 小时前
征程 6 | BPU trace 简介与实操
算法·自动驾驶
满天星83035776 小时前
【C++】AVL树的模拟实现
开发语言·c++·算法·stl
晓风凌殇6 小时前
单片机按键检测与长短按识别实现
c语言·单片机