请求开发判断字符串中是否存在符合特定连续数字规则的函数

Got it, let's break down how to solve this problem. The task is to write a function that takes a string (which has at least one character and includes digits 2-5) and returns "true" if any digit d (where 2 ≤ d ≤ 5) appears consecutively at least d times. If no such digit exists, return "false".

Approach #

Here's a straightforward, efficient way to handle this:

• Track the current digit we're counting and how many times it's appeared consecutively.
• As we iterate through the string:
  • If the next character matches the current digit, increment the count.
  • If it doesn't, check if the current digit meets our criteria (is 2-5, and count ≥ digit value). If yes, return "true" immediately.
  • Reset our tracking variables to the new digit and start counting from 1.
• Don't forget to check the last sequence of digits after the loop finishes—we might not have checked it yet!

Code Example (Python) #

def check_consecutive_digit_requirement(input_str):
    # Defensive check (though the problem states input has at least one element)
    if not input_str:
        return "false"
    
    # Initialize tracking variables with the first character
    current_digit = input_str[0]
    consecutive_count = 1
    
    for char in input_str[1:]:
        if char == current_digit:
            consecutive_count += 1
        else:
            # Check if the current sequence meets the criteria
            digit_value = int(current_digit)
            if 2 <= digit_value <= 5 and consecutive_count >= digit_value:
                return "true"
            # Reset for the new digit
            current_digit = char
            consecutive_count = 1
    
    # Check the final sequence after loop ends
    final_digit_value = int(current_digit)
    if 2 <= final_digit_value <= 5 and consecutive_count >= final_digit_value:
        return "true"
    
    # No valid sequences found
    return "false"

Test Cases #

Let's verify with your examples:

• Input: "555123" → The digit 5 runs 3 times (3 < 5), digits 2 and 3 each run once. No valid sequences, so returns "false".
• Input: "57333" → The digit 3 runs exactly 3 times (3 ≥ 3), so returns "true".

Additional Edge Cases to Consider #

• "22" → Returns "true" (2 runs 2 times)
• "444" → Returns "false" (4 runs 3 times, which is less than 4)
• "55555" → Returns "true" (5 runs 5 times)
• "332222" → Returns "true" (2 runs 4 times, which meets the ≥2 requirement)

内容的提问来源于stack exchange，提问作者chopin_is_the_best