字符串数组中最长的公共子串

我们得到了一个共享一个共同词干的词列表，即这些词来自同一个词，例如：词悲伤、悲伤和悲伤都来自词干'sad' 。
我们的任务是找到并返回最长的公共子串，也称为这些词的词干。如果有平局，我们会按字母顺序选择最小的一个。

例子：

Input : grace graceful disgraceful gracefully
Output : grace

Input : sadness sad sadly
Output : sad

这个想法是将列表中的任何单词作为参考，并形成其所有子字符串并遍历整个列表，检查生成的子字符串是否出现在所有子字符串中。

下面是上述思想的实现：

C++

// C++ program to find the stem of given list of
// words
#include 
using namespace std;
 
// function to find the stem (longest common
// substring) from the string array
string findstem(vector arr)
{
    // Determine size of the array
    int n = arr.size();
 
    // Take first word from array as reference
    string s = arr[0];
    int len = s.length();
 
    string res = "";
 
    for (int i = 0; i < len; i++) {
        for (int j = i + 1; j <= len; j++) {
            // generating all possible substrings
            // of our reference string arr[0] i.e s
            string stem = s.substr(i, j);
            int k = 1;
            for (k = 1; k < n; k++) {
                // Check if the generated stem is
                // common to all words
                if (arr[k].find(stem) == std::string::npos)
                    break;
            }
 
            // If current substring is present in
            // all strings and its length is greater
            // than current result
            if (k == n && res.length() < stem.length())
                res = stem;
        }
    }
 
    return res;
}
 
// Driver code
int main()
{
    vector arr{ "grace", "graceful", "disgraceful",
                        "gracefully" };
 
    // Function call
    string stems = findstem(arr);
    cout << stems << endl;
}
 
// This code is contributed by
// sanjeev2552

Java

// Java program to find the stem of given list of
// words
import java.io.*;
import java.util.*;
 
class stem {
 
    // function to find the stem (longest common
    // substring) from the string  array
    public static String findstem(String arr[])
    {
        // Determine size of the array
        int n = arr.length;
 
        // Take first word from array as reference
        String s = arr[0];
        int len = s.length();
 
        String res = "";
 
        for (int i = 0; i < len; i++) {
            for (int j = i + 1; j <= len; j++) {
 
                // generating all possible substrings
                // of our reference string arr[0] i.e s
                String stem = s.substring(i, j);
                int k = 1;
                for (k = 1; k < n; k++)
 
                    // Check if the generated stem is
                    // common to all words
                    if (!arr[k].contains(stem))
                        break;
 
                // If current substring is present in
                // all strings and its length is greater
                // than current result
                if (k == n && res.length() < stem.length())
                    res = stem;
            }
        }
 
        return res;
    }
 
    // Driver Code
    public static void main(String args[])
    {
        String arr[] = { "grace", "graceful",
                        "disgraceful","gracefully" };
       
        // Function call
        String stems = findstem(arr);
        System.out.println(stems);
    }
}

Python 3

# Python 3 program to find the stem
# of given list of words
 
# function to find the stem (longest
# common substring) from the string array
 
 
def findstem(arr):
 
    # Determine size of the array
    n = len(arr)
 
    # Take first word from array
    # as reference
    s = arr[0]
    l = len(s)
 
    res = ""
 
    for i in range(l):
        for j in range(i + 1, l + 1):
 
            # generating all possible substrings
            # of our reference string arr[0] i.e s
            stem = s[i:j]
            k = 1
            for k in range(1, n):
 
                # Check if the generated stem is
                # common to all words
                if stem not in arr[k]:
                    break
 
            # If current substring is present in
            # all strings and its length is greater
            # than current result
            if (k + 1 == n and len(res) < len(stem)):
                res = stem
 
    return res
 
 
# Driver Code
if __name__ == "__main__":
 
    arr = ["grace", "graceful",
           "disgraceful", "gracefully"]
     
    # Function call
    stems = findstem(arr)
    print(stems)
 
# This code is contributed by ita_c

C#

// C# program to find the stem of given list of
// words
using System;
using System.Collections.Generic;
 
class stem
{
    // function to find the stem (longest common
    // substring) from the string array
    public static String findstem(String []arr)
    {
        // Determine size of the array
        int n = arr.Length;
 
        // Take first word from array as reference
        String s = arr[0];
        int len = s.Length;
 
        String res = "";
 
        for (int i = 0; i < len; i++)
        {
            for (int j = i + 1; j <= len; j++)
            {
 
                // generating all possible substrings
                // of our reference string arr[0] i.e s
                String stem = s.Substring(i, j-i);
                int k = 1;
                for (k = 1; k < n; k++)
 
                    // Check if the generated stem is
                    // common to all words
                    if (!arr[k].Contains(stem))
                        break;
                 
                // If current substring is present in
                // all strings and its length is greater
                // than current result
                if (k == n && res.Length < stem.Length)
                    res = stem;
            }
        }
 
        return res;
    }
 
    // Driver Code
    public static void Main(String []args)
    {
        String []arr = { "grace", "graceful", "disgraceful",
                                            "gracefully" };
        // Function call
        String stems = findstem(arr);
        Console.WriteLine(stems);
    }
}
 
// This code contributed by Rajput-Ji

输出

grace