Check if a two character string can be made using given words

Last Updated : 20 Jul, 2022

Given a string of two characters and n distinct words of two characters. The task is to find if it is possible to arrange given words in such a way that the concatenated string has the given two character string as a substring. We can append a word multiple times.

Examples:

Input : str = "ya"         words[] = {"ah", "oy", "to", "ha"}  Output : YES We can join "oy" and then "ah", and then "ha" to form the string "oyahha"  which contains the string "ya".  So, the answer is "YES"  Input : str[] = "ha"         words[] = "ah" Output :YES The string "ahah" contains "ha"  as a substring.  Input : str = "hp"        words[] = {"ht", "tp"| Output :NO We can't produce a string containing "hp" as a sub-string. Note that we can join "ht" and then "tp" producing "http", but it doesn't contain the  "hp" as a sub-string.

If we look at the given examples carefully, we can see that our answer will be "YES" if any of the following conditions is true,

str is equal to any one of the N words
str is equal to reverse of any of the words.
It first letter of str is equal to last letter of any of the given N strings and last letter is equal to the first letter of any of the given N strings.

Otherwise our output will always be NO.

Below is the implementation of the above approach.

C++

// CPP code to check if a two character string can  // be made using given strings #include <bits/stdc++.h> using namespace std;  // Function to check if str can be made using // given words bool makeAndCheckString(vector<string> words, string str) {     int n = words.size();     bool first = false, second = false;      for (int i = 0; i < n; i++) {          // If str itself is present          if (words[i] == str)             return true;              // Match first character of str         // with second of word and vice versa         if (str[0] == words[i][1])              first = true;                     if (str[1] == words[i][0])              second = true;          // If both characters found.         if (first && second)             return true;      }          return false;  }  // Driver Code int main() {      string str = "ya";              vector<string> words = { "ah", "oy", "to", "ha"};          if (makeAndCheckString(words, str))        cout << "Yes";     else        cout << "No";     return 0; }

Java

// Java code to check if a two character string can  // be made using given strings import java.util.*;  class GFG {  // Function to check if str can be made using // given words static boolean makeAndCheckString(Vector<String> words,                                              String str) {     int n = words.size();     boolean first = false, second = false;      for (int i = 0; i < n; i++)      {          // If str itself is present          if (words.get(i) == str)             return true;              // Match first character of str         // with second of word and vice versa         if (str.charAt(0) == words.get(i).charAt(1))              first = true;                  if (str.charAt(1) == words.get(i).charAt(0))              second = true;          // If both characters found.         if (first && second)             return true;      }          return false;  }  // Driver Code public static void main(String[] args)  {     String str = "ya";      String[] array = { "ah", "oy", "to", "ha"};     Vector<String> words = new Vector<String>(Arrays.asList(array));          if (makeAndCheckString(words, str))         System.out.println("Yes");     else         System.out.println("No"); } }  // This code is contributed by 29AjayKumar

Python3

# Python3 code to check if a two character string can   # be made using given strings   # Function to check if str can be made using  # given words  def makeAndCheckString(words, str):     n = len(words)     first = second = False      for i in range(n):         # If str itself is present         if words[i]==str:             return True          # Match first character of str          # with second of word and vice versa          if str[0] == words[i][1]:             first = True         if str[1] == words[i][0]:             second = True          # If both characters found.         if first and second:             return True          return False      # Driver Code  str = 'ya' words = ['ah', 'oy', 'to', 'ha'] if makeAndCheckString(words, str):     print('YES') else:     print('NO')  # This code is contributed   # by SamyuktaSHegde

// C# code to check if a two character string can  // be made using given strings using System;  using System.Collections.Generic;   class GFG {  // Function to check if str can be made using // given words static bool makeAndCheckString(List<String> words,                                              String str) {     int n = words.Count;     bool first = false, second = false;      for (int i = 0; i < n; i++)      {          // If str itself is present          if (words[i] == str)             return true;              // Match first character of str         // with second of word and vice versa         if (str[0] == words[i][1])              first = true;                  if (str[1] == words[i][0])              second = true;          // If both characters found.         if (first && second)             return true;      }          return false;  }  // Driver Code public static void Main(String[] args)  {     String str = "ya";      String[] array = { "ah", "oy", "to", "ha"};     List<String> words = new List<String>(array);          if (makeAndCheckString(words, str))         Console.WriteLine("Yes");     else         Console.WriteLine("No"); } }  // This code is contributed by Princi Singh

PHP

<?php // PHP code to check if a two character string can  // be made using given strings   // Function to check if str can be made using  // given words  function makeAndCheckString($words, $str)  {     $n = sizeof($words) ;     $first = false ;     $second = false;       for ($i = 0; $i < $n; $i++) {           // If str itself is present          if ($words[$i] == $str)              return true;               // Match first character of str          // with second of word and vice versa          if ($str[0] == $words[$i][1])              $first = true;                      if ($str[1] == $words[$i][0])              $second = true;           // If both characters found.          if ($first && $second)              return true;      }           return false;  }       // Driver Code       $str = "ya";              $words = array( "ah", "oy", "to", "ha") ;     if (makeAndCheckString($words, $str))          echo "Yes";      else         echo "No";       // This code is contributed by Ryuga ?>

JavaScript

<script>     // Javascript code to check if a two character string can      // be made using given strings          // Function to check if str can be made using     // given words     function makeAndCheckString(words, str)     {         let n = words.length;         let first = false, second = false;          for (let i = 0; i < n; i++)          {              // If str itself is present              if (words[i] == str)                 return true;              // Match first character of str             // with second of word and vice versa             if (str[0] == words[i][1])                  first = true;                      if (str[1] == words[i][0])                  second = true;              // If both characters found.             if (first && second)                 return true;          }          return false;      }          let str = "ya";      let words = [ "ah", "oy", "to", "ha"];         if (makeAndCheckString(words, str))         document.write("YES");     else         document.write("NO");          // This code is contributed by suresh07. </script>

Output

Yes

Time Complexity: O(n), where n represents the size of the given vector.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

Check if characters of a given string can be used to form any N equal strings

Sarthak Kohli

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Check if a two character string can be made using given words

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