String (C++ / Python) timer 1s memory 256MB

Many students have difficulty handling strings.
Therefore, today we will introduce an easier and simpler way to work with strings.

C++

The C++ string class is a class for handling strings.
Unlike C's char* or char[] strings, C++ strings do not have a terminating '\0' character and their length can change dynamically.

However, std::string cannot be directly input using scanf.
So, you should use C++ standard input/output cin and cout.

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string word, sentence; // declare two strings

    cin >> word; // input until a space (or enter)
    cin.ignore(); // remove one character from input buffer (needed before getline to remove '\n', don't use if getline is used alone)
    getline(cin, sentence); // input the rest of the line including spaces until '\n'

    cout << word << '\n';       // output
    cout << sentence << '\n';   // output

    return 0;
}

Using the string class is convenient because operators can be used.
You can use ==, <, >, +, etc.

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string a = "abc", b = "de", c;
    // If a equals b, c will be the same as a.
    // If a is lexicographically smaller than b, c will be a concatenated with b.
    // Otherwise, c will be b concatenated with a.

    if(a == b) c = a;       // c = "abc"
    else if(a < b) c = a + b; // c = "abcde"
    else c = b + a;         // c = "deabc"

    cout << c;

    return 0;
}

You can also easily manipulate strings using various functions.

Let’s learn these functions using the following example:

• Get string length: length()

• Find the index of another string: find(other_string)

• Extract a substring: substr(start_index, length)

• Erase a part of the string: erase(start_index, length)

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string A = "I love coding!";

    // Get length of A
    int len = (int) A.length(); // len: 14

    // Find index of substring "coding"
    int idx = A.find("coding"); // idx: 7

    // Find index of substring "abc"
    int x = A.find("abc"); // if not found, returns string::npos

    // Extract substring of length 4 from index 2: "love"
    string sub = A.substr(2, 4);

    // Delete substring of length 5 starting from index 1
    A.erase(1, 5); // A: "I coding!"

    cout << len << "\n" << idx << "\n" << x << "\n" << sub << "\n" << A;
    return 0;
}

#include <stdio.h>
#include <string>
using namespace std;

int main()
{
    char _word[105], _sent[105];
    scanf("%s %[^\r\n]", _word, _sent); 
    
    string word = _word, sent = _sent;
    word += '!';
    sent += '?';

    strcpy(_word, word.c_str());  
    strcpy(_sent, sent.c_str());
    printf("%s\n%s", _word, _sent);

    return 0;
}

Python

• Get string length: len()

• Find index of substring: find(other_string)

• Extract substring: slicing [start_index : end_index] (end_index not included)

• Remove part of a string: replace(old, new[, count])

A = "I love coding!"

# Get length
length = len(A)     # length: 14

# Find index of "coding"
idx = A.find("coding")     # idx: 7

# Find index of "abc"
x = A.find("abc")   # if not found, returns -1

# Extract substring from index 2 to 5: "love"
sub = A[2:6]

# Remove "co" from string
A = A.replace('co', '') # A: "I love ding!"

print(length, idx, sub)
print(A)

[Problem]

Write a program that satisfies the following conditions:

1. Input two strings: S and T.

2. Starting from the first character of S, check for T. When T appears, remove it and concatenate the remaining parts.

3. Repeat step 2 until T no longer appears in S.

4. Output the remaining string S.