C++ Level 3 Exercise: Substring Verification (luogu-B2118)

This is a Level 3 exercise in GESP, focusing on string manipulation (Knowledge Point 6 in the C++ Level 3 syllabus), Difficulty ★★☆☆☆.

luogu-B2118 Substring Verification

Problem Requirements

Problem Description

Input two strings and verify if one string is a substring of the other.

Input Format

Two lines, each containing one string.

Output Format

If the first string is a substring of the second string, output<span>(s1) is substring of (s2)</span>;

Otherwise, if the second string is a substring of the first string, output<span>(s2) is substring of (s1)</span>;

If neither is true, output <span>No substring</span>.

Input/Output Example #1

Input #1

abc
dddncabca

Output #1

abc is substring of dddncabca

Input/Output Example #2

Input #2

aaa
bbb

Output #2

No substring

Notes/Tips

For the data of , the string length is within .

Problem Analysis

Solution Approach

1. The problem requires normalizing the case format of drug names.

2. Normalization rules analysis:

• The first letter needs to be capitalized
• All other letters need to be lowercase
• Numbers and special characters (like “-“) remain unchanged

Specific approach:

• Read the number of drugs and the drug names
• Process each drug name:
• Check the first character; if it is a letter, convert it to uppercase
• Convert the remaining characters to lowercase
• Keep numbers and special characters unchanged
• Output the processed result

1. Time complexity analysis:

• Each drug name’s characters need to be traversed,
• where is the number of drugs, is the maximum length of the drug names
• Space complexity is , requiring storage for n strings of length m

Example Code

#include <cstdio>
#include <iostream>
#include <string>

int main() {
    // Declare two string variables to store input
    std::string str1;
    std::string str2;
    // Use getline to read two lines of input, each containing one string
    std::getline(std::cin, str1);
    std::getline(std::cin, str2);
    // Check if str1 contains str2
    if (str1.find(str2) != std::string::npos) {
        // If str2 is a substring of str1, output the result in the specified format
        printf("%s is substring of %s", str2.c_str(), str1.c_str());
    } 
    // Check if str2 contains str1
    else if (str2.find(str1) != std::string::npos) {
        // If str1 is a substring of str2, output the result in the specified format
        printf("%s is substring of %s", str1.c_str(), str2.c_str());
    } 
    // If neither string is a substring of the other
    else {
        std::cout << "No substring";
    }
    return 0;
}

For more details on GESP levels, past exam questions, knowledge expansion, and practice lists, see:

【Top】【GESP】C++ Certification Learning Resources Summary

The “luogu-” series problems can be evaluated online atLuogu Problem Bank.

The “bcqm-” series problems can be evaluated online atProgramming Enlightenment Problem Bank.