Given a binary string str consisting of characters ‘0’ and ‘1’. The task is to find whether the string is valid or not. A string is valid only if the characters are alternating i.e. no two consecutive characters are the same.
Examples:
Input: str[] = “010101”
Output: ValidInput: str[] = “010010”
Output: Invalid
Approach: Start traversing the string character by character and if there are any two consecutive characters that are equal then print Invalid else print Valid in the end.
Below is the implementation of the above approach:
C++
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std;// Function that returns true is str is validbool isValid(string str, int len){ // Assuming the string is binary // If any two consecutive characters are equal // then the string is invalid for (int i = 1; i < len; i++) { if (str[i] == str[i - 1]) return false; } // If the string is alternating return true;}// Driver codeint main(){ string str = "0110"; int len = str.length(); if (isValid(str, len)) cout << "Valid"; else cout << "Invalid"; return 0;} |
Java
// Java implementation of the approachclass gfg{ // Function that returns true is str is validstatic boolean isValid(String str, int len){ // Assuming the string is binary // If any two consecutive // characters are equal // then the string is invalid for (int i = 1; i < len; i++) { if (str.charAt(i) == str.charAt(i - 1)) return false; } // If the string is alternating return true;}// Driver codepublic static void main(String[] args){ String str = "0110"; int len = str.length(); if (isValid(str, len)) System.out.println("Valid"); else System.out.println("Invalid");}}// This code is Contributed by Code_Mech |
Python3
# Python3 implementation of the approach # Function that returns true is str is valid def isValid(string, length): # Assuming the string is binary # If any two consecutive characters # are equal then the string is invalid for i in range(1, length): if string[i] == string[i - 1]: return False # If the string is alternating return True# Driver code if __name__ == "__main__": string = "0110" length = len(string) if isValid(string, length): print("Valid") else: print("Invalid") # This code is contributed by Rituraj Jain |
C#
// C# implementation of the approachusing System;class gfg{ // Function that returns true is str is validstatic bool isValid(string str, int len){ // Assuming the string is binary // If any two consecutive // characters are equal // then the string is invalid for (int i = 1; i < len; i++) { if (str[i] == str[i - 1]) return false; } // If the string is alternating return true;}// Driver codepublic static void Main(){ string str = "0110"; int len = str.Length; if (isValid(str, len)) Console.Write("Valid"); else Console.Write("Invalid");}}// This code is contributed by Ita_c. |
PHP
<?php// PHP implementation of the approach // Function that returns true is str is valid function isValid($str, $len) { // Assuming the string is binary // If any two consecutive characters // are equal then the string is invalid for ($i = 1; $i < $len; $i++) { if ($str[$i] == $str[$i - 1]) return false; } // If the string is alternating return true; } // Driver code $str = "0110"; $len = strlen($str); if (isValid($str, $len)) echo "Valid"; else echo "Invalid"; // This code is contributed by Ryuga?> |
Javascript
<script>// Javascript implementation of the approach// Function that returns true is str is validfunction isValid(str,len){ // Assuming the string is binary // If any two consecutive // characters are equal // then the string is invalid for (let i = 1; i < len; i++) { if (str[i] == str[i - 1]) return false; } // If the string is alternating return true;}// Driver codelet str = "0110";let len = str.length;if (isValid(str, len)) document.write("Valid");else document.write("Invalid");// This code is contributed by rag2127</script> |
Output
Invalid
Time Complexity: O(N), where N is the length of the string.
Auxiliary Space: O(1), As constant extra space is used.
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