Openjudge noi 1.7 10: simple password

【 Topic link 】

OpenJudge NOI 1.7 10: Simple code

【 Topic test site 】

1. ASCII code

2. character string

【 Their thinking 】

We can know by analyzing the law , The plaintext letter is the first number of ciphertext characters 5 Letters .

solution 1： Letters correspond to numbers

Put the letters c Turn to the corresponding number ,A Corresponding number 0,B Corresponding number 1… Z Corresponding number 25, Method is c - 'A'

• If c - 'A' >= 5, Then the number corresponding to the plaintext letter is c - 'A' - 5
• If c - 'A' < 5, Then the number corresponding to the plaintext letter is c - 'A' + 26 - 5
  Last , Then turn numbers into characters
  Finally integrated into c = (c - 'A' + 26 - 5) % 26 + 'A'

solution 2： Directly judge the current letter ASCII code

If the current ciphertext alphabet variable c yes ’E’ And ’E’ The previous letter , Then the corresponding plaintext letter is c+21
If the current ciphertext alphabet variable c yes ’F’ And ’F‘ The letter after , Then the corresponding plaintext letter is c-5

【 Solution code 】

solution 1： A character array Letters correspond to numbers

#include<bits/stdc++.h>
using namespace std;
int main()
{
    
    char s[205];
	cin.getline(s, 205);
	int len = strlen(s);
	for(int i = 0; i < len; ++i)
	{
    
		if(s[i] >= 'A' && s[i] <= 'Z')
			s[i] = (s[i] - 'A' + 26 - 5) % 26 + 'A';
	}
	cout << s;
	return 0;
}

solution 2：string class Judge the character ASCII code

#include<bits/stdc++.h>
using namespace std;
int main()
{
    
    string s; 
	getline(cin, s);
	for(int i = 0; i < s.length(); ++i)
	{
    
		if(s[i] >= 'A' && s[i] <= 'E')
			s[i] = s[i] + 21;
		else if(s[i] >= 'F' && s[i] <= 'Z')
			s[i] = s[i] - 5;
	}
	cout << s;
	return 0;
}

solution 3： Keep reading in characters , Judge output

#include<bits/stdc++.h>
using namespace std;
int main()
{
    
    char c;
    c = getchar();
    while(c != '\n')
    {
    
        if (c >= 'A' && c <= 'Z')
            putchar((c - 'A' - 5 + 26) % 26 + 'A');
        else
            putchar(c);
        c = getchar();
    }
    return 0;
}