检查三个或更多连续的相同字符或数字

给定字符串str ，任务是使用正则表达式检查给定字符串是否包含3个或更多连续的相同字符/数字。
例子：

Input: str = “aaa”; 
Output: true 
Explanation: 
The given string contains a, a, a which are consecutive identical characters.
Input: str = “abc”; 
Output: false 
Explanation: 
The given string contains a, b, c which are not consecutive identical characters.
Input: str = “11”; 
Output: false 
Explanation: 
The given string contains 1, 1 which are not 3 or more consecutive identical numbers. 

方法：想法是使用正则表达式解决此问题。可以按照以下步骤计算答案。

• 获取字符串。
• 创建一个正则表达式以检查3个或更多连续的相同字符或数字，如下所述：

regex = “\\b([a-zA-Z0-9])\\1\\1+\\b”; 
 

• 在哪里：
  • \\ b表示单词边界。
  • (代表第1组的开始。
  • [a-zA-Z0-9]表示字母或数字。
  • )代表第1组的结尾。
  • \\ 1代表与组1相同的字符。
  • \\ 1+代表与组1相同的字符一次或多次。
  • \\ b表示单词边界。

1. 将给定的字符串与正则表达式匹配。在Java，这可以通过使用Pattern.matcher()来完成。
2. 如果字符串与给定的正则表达式匹配，则返回true；否则返回false。

下面是上述方法的实现：

C++

// C++ program to check
// three or more consecutive identical
// characters or numbers using Regular Expression
#include 
#include 
using namespace std;
 
// Function to check three or more
// consecutive identical characters or numbers.
bool isIdentical(string str)
{
 
  // Regex to check valid three or more
  // consecutive identical characters or numbers.
  const regex pattern("\\b([a-zA-Z0-9])\\1\\1+\\b");
 
 
  // If the three or more consecutive
  // identical characters or numbers
  // is empty return false
  if (str.empty())
  {
     return false;
  }
 
  // Return true if the three or more
  // consecutive identical characters or numbers
  // matched the ReGex
  if(regex_match(str, pattern))
  {
    return true;
  }
  else
  {
    return false;
  }
}
 
// Driver Code
int main()
{
   
  // Test Case 1:
  string str1 = "aaa";
  cout << isIdentical(str1) << endl;
 
  // Test Case 2:
  string str2 = "11111";
  cout << isIdentical(str2) << endl;
 
  // Test Case 3:
  string str3 = "aaab";
  cout << isIdentical(str3) << endl;
 
  // Test Case 4:
  string str4 = "abc";
  cout << isIdentical(str4) << endl;
 
  // Test Case 5:
  string str5 = "aa";
  cout << isIdentical(str5) << endl;
  return 0;
}
 
// This code is contributed by yuvraj_chandra

Java

// Java program to check three or
// more consecutive identical
// characters or numbers
// using regular expression
 
import java.util.regex.*;
class GFG {
 
    // Function to check three or
    // more consecutive identical
    // characters or numbers
    // using regular expression
    public static boolean isIdentical(String str)
    {
        // Regex to check three or
        // more consecutive identical
        // characters or numbers
        String regex
            = "\\b([a-zA-Z0-9])\\1\\1+\\b";
 
        // Compile the ReGex
        Pattern p
            = Pattern.compile(regex);
 
        // If the string is empty
        // return false
        if (str == null) {
            return false;
        }
 
        // Find match between given string
        // and regular expression
        // using Pattern.matcher()
        Matcher m = p.matcher(str);
 
        // Return if the string
        // matched the ReGex
        return m.matches();
    }
 
    // Driver code
    public static void main(String args[])
    {
 
        // Test Case 1:
        String str1 = "aaa";
        System.out.println(
            isIdentical(str1));
 
        // Test Case 2:
        String str2 = "11111";
        System.out.println(
            isIdentical(str2));
 
        // Test Case 3:
        String str3 = "aaab";
        System.out.println(
            isIdentical(str3));
 
        // Test Case 4:
        String str4 = "abc";
        System.out.println(
            isIdentical(str4));
 
        // Test Case 5:
        String str5 = "aa";
        System.out.println(
            isIdentical(str5));
    }
}

Python3

# Python3 program to check three or
# more consecutiveidentical
# characters or numbers
# using regular expression
import re
 
# Function to check three or
# more consecutiveidentical
# characters or numbers
# using regular expression
def isValidGUID(str):
 
    # Regex to check three or
    # more consecutive identical
    # characters or numbers
    regex = "\\b([a-zA-Z0-9])\\1\\1+\\b"
     
    # Compile the ReGex
    p = re.compile(regex)
 
    # If the string is empty
    # return false
    if (str == None):
        return False
 
    # Return if the string
    # matched the ReGex
    if(re.search(p, str)):
        return True
    else:
        return False
 
# Driver code
 
# Test Case 1:
str1 = "aaa"
print(isValidGUID(str1))
 
# Test Case 2:
str2 = "11111"
print(isValidGUID(str2))
 
# Test Case 3:
str3 = "aaab"
print(isValidGUID(str3))
 
# Test Case 4:
str4 = "abc"
print(isValidGUID(str4))
 
# Test Case 4:
str5 = "aa"
print(isValidGUID(str5))
 
# This code is contributed by avanitrachhadiya2155

输出：

true
true
false
false
false