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# Use urllib.request to send network request if needed.
import fileinput
// ... rest of solution available after purchaseExplanation
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To solve the problem of checking whether each string in an array T exists within a larger string S, while ignoring case differences, you should approach it with careful consideration of string matching principles and case-insensitive comparison.
Start by understanding the input and output requirements clearly. You have a long string S and an array T containing multiple smaller strings. For each string in T, you must determine if it appears as a substring anywhere within S, regardless of letter casing. The output for each string in T is typically a boolean or a message indicating presence or absence.
The key challenges here are:
1. **Case Insensitivity:** You need to treat uppercase and lowercase letters as equivalent when searching for substrings. This means "Coffee" and "coffee" should be considered a match. To handle this, think about normalizing both the main string S and each query string in T to a common case, either all lowercase or all uppercase, before performing the substring search.
2. **Substring Matching:** The core operation is to check if a smaller string exists inside a larger string. This is a standard substring search problem. Most programming languages provide built-in functions or methods for substring searching, which can be leveraged. Alternatively, more advanced substring searching algorithms (like KMP or Rabin-Karp) exist but are generally unnecessary unless the strings are extremely large and performance is critical.
3. **Handling Spaces and Special Characters:** The strings in T might contain spaces or special characters. When performing the search, consider these as literal characters. The problem statement doesn't indicate removing or ignoring spaces or special characters, so treat them as part of the substring pattern. For example, searching for "hot coffee" inside "coffeeshop" should return false because there is no space in "coffeeshop" matching the space in "hot coffee."
4. **Multiple Queries:** Since T contains multiple strings, iterate through each string in T and apply the same case-insensitive substring check independently. Store or print the results accordingly.
Steps to approach the problem:
- **Normalize the strings:** Convert the large string S to a consistent case, such as all lowercase. Similarly, convert each string in the array T to the same case. This ensures the comparison is case-insensitive.
- **Search for each string:** For every string in T, check if it is a substring of the normalized S. This can be done using built-in substring functions, which often run efficiently for typical input sizes.
- **Output results:** For each query string, output whether it is contained in S or not. This could be a boolean array, a list of strings with messages, or any format that clearly conveys the presence or absence.
- **Edge Cases:** Consider special cases such as:
- Empty strings in T, which trivially exist as substrings.
- Strings in T that are longer than S, which cannot be substrings.
- Strings with only spaces or special characters.
- Strings that match at the very beginning or end of S.
- The large string S being empty.
Additional considerations:
- **Performance:** If S is very large and T contains many strings, performance might be a concern. Although built-in substring checks are usually optimized, if you face performance bottlenecks, consider preprocessing techniques such as suffix trees or suffix arrays, which allow faster repeated substring searches but are more complex to implement.
- **Memory usage:** Normalizing to lowercase involves creating new strings in memory. This is usually not a problem, but be mindful if the input strings are huge.
- **Correctness:** Always confirm that you apply case normalization consistently on both the main string and the query strings. Mismatched casing would lead to incorrect results.
To summarize, the problem reduces to performing multiple case-insensitive substring searches. The essential approach is to:
1. Convert the large string S to a single consistent case.
2. Convert each query string in T to the same case.
3. Use a substring search function to check if each query is found in S.
4. Output the results clearly.
This approach ensures accuracy, clarity, and efficiency, leveraging straightforward string manipulation techniques and built-in substring search functionalities. By thinking along these lines, you will create a solution that handles all typical and edge cases effectively.
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