最长的子串，使得没有三个连续字符相同

给定字符串str ，任务是找到str的最长子字符串的长度，使得子字符串中没有三个连续字符相同。
例子：

Input: str = “baaabbabbb”
Output: 7
“aabbabb” is the required substring.
Input: str = “babba”
Output: 5
Given string itself is the longest substring.

编程需要懂一点英语

方法：可以按照以下步骤解决问题：

如果给定字符串的长度小于3 ，那么字符串的长度就是答案。
最初将temp和ans初始化为2 ，因为当给定字符串的长度大于2时，这是最长子字符串的最小长度。
如果str[i] != str[i – 1]或str[i] != str[i – 2]则在字符串中从2迭代到N – 1并将 temp 增加1 。
否则重新初始化temp = 2和 ans = max(ans, temp)。

下面是上述方法的实现：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
// Function to return the length of the
// longest substring such that no three
// consecutive characters are same
int maxLenSubStr(string& s)
{
    // If the length of the given string
    // is less than 3
    if (s.length() < 3)
        return s.length();
 
    // Initialize temporary and final ans
    // to 2 as this is the minimum length
    // of substring when length of the given
    // string is greater than 2
    int temp = 2;
    int ans = 2;
 
    // Traverse the string from the
    // third character to the last
    for (int i = 2; i < s.length(); i++) {
 
        // If no three consecutive characters
        // are same then increment temporary count
        if (s[i] != s[i - 1] || s[i] != s[i - 2])
            temp++;
 
        // Else update the final ans and
        // reset the temporary count
        else {
            ans = max(temp, ans);
            temp = 2;
        }
    }
 
    ans = max(temp, ans);
 
    return ans;
}
 
// Driver code
int main()
{
    string s = "baaabbabbb";
 
    cout << maxLenSubStr(s);
 
    return 0;
}

Java

// Java implementation of the approach
import java.util.*;
 
class GFG
{
 
// Function to return the length of the
// longest substring such that no three
// consecutive characters are same
static int maxLenSubStr(String s)
{
    // If the length of the given string
    // is less than 3
    if (s.length() < 3)
        return s.length();
 
    // Initialize temporary and final ans
    // to 2 as this is the minimum length
    // of substring when length of the given
    // string is greater than 2
    int temp = 2;
    int ans = 2;
 
    // Traverse the string from the
    // third character to the last
    for (int i = 2; i < s.length(); i++)
    {
 
        // If no three consecutive characters
        // are same then increment temporary count
        if (s.charAt(i) != s.charAt(i - 1) ||
            s.charAt(i) != s.charAt(i - 2))
            temp++;
 
        // Else update the final ans and
        // reset the temporary count
        else
        {
            ans = Math.max(temp, ans);
            temp = 2;
        }
    }
    ans = Math.max(temp, ans);
 
    return ans;
}
 
// Driver code
public static void main(String[] args)
{
    String s = "baaabbabbb";
 
    System.out.println(maxLenSubStr(s));
}
}
 
// This code is contributed by PrinciRaj1992

Python3

# Python3 implementation of the approach
 
# Function to return the length of the
# longest substring such that no three
# consecutive characters are same
def maxLenSubStr(s):
     
    # If the length of the given string
    # is less than 3
    if (len(s) < 3):
        return len(s)
 
    # Initialize temporary and final ans
    # to 2 as this is the minimum length
    # of substring when length of the given
    # string is greater than 2
    temp = 2
    ans = 2
 
    # Traverse the string from the
    # third character to the last
    for i in range(2, len(s)):
 
        # If no three consecutive characters
        # are same then increment temporary count
        if (s[i] != s[i - 1] or s[i] != s[i - 2]):
            temp += 1
 
        # Else update the final ans and
        # reset the temporary count
        else:
            ans = max(temp, ans)
            temp = 2
    ans = max(temp, ans)
 
    return ans
 
# Driver code
s = "baaabbabbb"
 
print(maxLenSubStr(s))
 
# This code is contributed by Mohit Kumar

C#

// C# implementation of the approach
using System;
 
class GFG
{
     
// Function to return the length of the
// longest substring such that no three
// consecutive characters are same
static int maxLenSubStr(String s)
{
    // If the length of the given string
    // is less than 3
    if (s.Length < 3)
        return s.Length;
 
    // Initialize temporary and final ans
    // to 2 as this is the minimum length
    // of substring when length of the given
    // string is greater than 2
    int temp = 2;
    int ans = 2;
 
    // Traverse the string from the
    // third character to the last
    for (int i = 2; i < s.Length; i++)
    {
 
        // If no three consecutive characters
        // are same then increment temporary count
        if (s[i] != s[i - 1] ||
            s[i] != s[i - 2])
            temp++;
 
        // Else update the final ans and
        // reset the temporary count
        else
        {
            ans = Math.Max(temp, ans);
            temp = 2;
        }
    }
    ans = Math.Max(temp, ans);
 
    return ans;
}
 
// Driver code
static public void Main ()
{
    String s = "baaabbabbb";
    Console.Write(maxLenSubStr(s));
}
}
 
// This code is contributed by ajit.

Javascript

输出：

时间复杂度： O(N) 其中 N 是字符串的长度。
空间复杂度： O(1)