使用链表的最长公共前缀

给定一组字符串，找出最长的公共前缀。

例子：

Input  : {“geeksforgeeks”, “geeks”, “geek”, “geezer”}
Output : "gee"

Input  : {"apple", "ape", "april"}
Output : "ap"

以前的方法：逐字匹配、逐字符匹配、分而字符之、二分查找、使用 Trie 数据结构

下面是使用Linked List解决上述问题的算法。

• 使用第一个字符串的字符作为链表中的数据创建链表。
• 然后一一使用所有剩余的字符串，遍历链表，删除字符串耗尽或链表耗尽或字符不匹配的点之后的所有节点。
• 链表中剩余的数据是所需的最长公共前缀。

下面是 C++ 中的实现

// C++ Program to find the longest common prefix
// in an array of strings
#include 
using namespace std;
  
// Structure for a node in the linked list
struct Node {
    char data;
    Node* next;
};
  
// Function to print the data in the linked list
// Remaining nodes represent the longest common prefix
void printLongestCommonPrefix(Node* head)
{
    // If the linked list is empty there is 
    // no common prefix
    if (head == NULL) {
        cout << "There is no common prefix\n";
        return;
    }
  
    // Printing the longest common prefix
    cout << "The longest common prefix is ";
    while (head != NULL) {
        cout << head->data;
        head = head->next;
    }
}
  
// Function that creates a linked list of characters
// for the first word in the array of strings
void Initialise(Node** head, string str)
{
    // We calculate the length of the string
    // as we will insert from the last to the 
    // first character
    int l = str.length();
  
    // Inserting all the nodes with the characters
    // using insert at the beginning technique
    for (int i = l - 1; i >= 0; i--) {
        Node* temp = new Node;
        temp->data = str[i];
        temp->next = *head;
        *head = temp;
    }
  
    // Since we have passed the address of the 
    // head node it is not required to return 
    // anything
}
  
// Function to delete all the nodes
// from the unmatched node till the end of the 
// linked list
void deleteNodes(Node* head)
{
    // temp is used to facilitate the deletion of nodes
    Node* current = head;
    Node* next;
    while (current != NULL) {
        next = current->next;
        free(current);
        current = next;
    }
}
  
// Function that compares the character of the string with
// the nodes of the linked list and deletes all nodes after
// the characters that do not match
void longestCommonPrefix(Node** head, string str)
{
    int i = 0;
  
    // Use the pointer to the previous node to
    // delete the link between the unmatched node 
    // and its prev node
    Node* temp = *head;
    Node* prev = *head;
    while (temp != NULL) {
  
        // If the current string finishes or if the
        // the characters in the linked list do not match
        // with the character at the corresponding position
        // delete all the nodes after that.
        if (str[i] == '\0' || temp->data != str[i]) {
  
            // If the first node does not match then there
            // is no common prefix
            if (temp == *head) {
                free(temp);
                *head = NULL;
            }
  
            // Delete all the nodes starting from the
            // unmatched node
            else {
                prev->next = NULL;
                deleteNodes(temp);
            }
            break;
        }
  
        // If the character matches, move to next 
        // node and store the address of the current 
        // node in prev
        prev = temp;
        temp = temp->next;
        i++;
    }
}
  
int main()
{
    string arr[] = { "geeksforgeeks", "geeks", "geek", "geezer",
                     "geekathon" };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    struct Node* head = NULL;
  
    // A linked list is created with all the characters
    // of the first string
    Initialise(&head, arr[0]);
  
    // Process all the remaining strings to find the 
    // longest common prefix
    for (int i = 1; i < n; i++)
        longestCommonPrefix(&head, arr[i]);
  
    printLongestCommonPrefix(head);
}

输出：

The longest common prefix is gee