给定由字母和数字字符组成的加密字符串str ，任务是解密该字符串并找到加密的消息。
为了解密该消息，找到代表单个字母字符的每个数字字符簇，这些数字字符可以通过用26计算数字的模数而获得，并且可以将范围为[0，25]的值映射为字符[ ‘a’，’z’]。
例如，如果str =“ 32ytAAcV4ui30hf10hj18”，则数字字符的簇将为{ 32，4，30，10，18 } ，它在对26进行模数运算后得到{ 6，4，4，10，18 }并可以进行映射到{‘g’，’e’，’e’，’k’，’s’}
例子：
Input: str = “this50hi4huji70”
Output: geeks
Input: str = “a1s2d3f3”
Output: bcdd
方法：想法是在字符串逐个遍历每个字符，然后检查它是否为数字字符。如果是，则将其串联为一个字符串。最后，用26为该数字字符串模。
在进行模运算时，我们不能简单地执行x％26，因为该数字可能太大，并且会导致整数溢出。
为了解决这个问题，我们将一一处理所有数字，并使用
(A * B)mod C =((A mod C)*(B mod C))mod C
然后，最后通过0，1，2，3，… 25 ‘A’， ‘B’， ‘C’，… ‘Z’，串联的所有字符解码回到每个整数字符和打印的最终结果。
下面是上述方法的实现：
C++
// C++ implementation of the approach
#include
using namespace std;
const int MOD = 26;
// Function that returns (num % 26)
int modulo_by_26(string num)
{
// Initialize result
int res = 0;
// One by one process all digits of 'num'
for (int i = 0; i < num.length(); i++)
res = (res * 10 + (int)num[i] - '0') % MOD;
return res;
}
// Function to return the decrypted string
string decrypt_message(string s)
{
// To store the final decrypted answer
string decrypted_str = "";
string num_found_so_far = "";
// One by one check for each character
// if it is a numeric character
for (int i = 0; i < s.length(); ++i) {
if (s[i] >= '0' && s[i] <= '9') {
num_found_so_far += s[i];
}
else if (num_found_so_far.length() > 0) {
// Modulo the number found in the string by 26
decrypted_str += 'a'
+ modulo_by_26(num_found_so_far);
num_found_so_far = "";
}
}
if (num_found_so_far.length() > 0) {
decrypted_str += 'a'
+ modulo_by_26(num_found_so_far);
}
return decrypted_str;
}
// Driver code
int main()
{
string s = "32ytAAcV4ui30hf10hj18";
// Print the decrypted string
cout << decrypt_message(s);
return 0;
} Java
// Java implementation of the approach
import java.util.*;
class GFG{
static int MOD = 26;
// Function that returns (num % 26)
static int modulo_by_26(String num)
{
// Initialize result
int res = 0;
// One by one process all digits of 'num'
for(int i = 0; i < num.length(); i++)
{
res = ((res * 10 +
(int)num.charAt(i) - '0') % MOD);
}
return res;
}
// Function to return the decrypted String
static String decrypt_message(String s)
{
// To store the final decrypted answer
String decrypted_str = "";
String num_found_so_far = "";
// One by one check for each character
// if it is a numeric character
for(int i = 0; i < s.length(); ++i)
{
if (s.charAt(i) >= '0' && s.charAt(i) <= '9')
{
num_found_so_far += s.charAt(i);
}
else if (num_found_so_far.length() > 0)
{
// Modulo the number found in the String by 26
decrypted_str += (char)('a' +
modulo_by_26(num_found_so_far));
num_found_so_far = "";
}
}
if (num_found_so_far.length() > 0)
{
decrypted_str += (char)('a' +
modulo_by_26(num_found_so_far));
}
return decrypted_str;
}
// Driver code
public static void main(String[] args)
{
String s = "32ytAAcV4ui30hf10hj18";
// Print the decrypted string
System.out.print(decrypt_message(s));
}
}
// This code is contributed by amal kumar choubeyPython3
# Python3 implementation of
# the approach
MOD = 26
# Function that returns
# (num % 26)
def modulo_by_26(num):
# Initialize result
res = 0
# One by one process all
# digits of 'num'
for i in range(len(num)):
res = ((res * 10 + ord(num[i]) -
ord('0')) % MOD)
return res
# Function to return the
# decrypted string
def decrypt_message(s):
# To store the final
# decrypted answer
decrypted_str = ""
num_found_so_far = ""
# One by one check for
# each character if it
# is a numeric character
for i in range(len(s)):
if (s[i] >= '0' and
s[i] <= '9'):
num_found_so_far += s[i]
elif (len(num_found_so_far) > 0):
# Modulo the number found
# in the string by 26
decrypted_str += chr(ord('a') +
(modulo_by_26(num_found_so_far)))
num_found_so_far = ""
if (len(num_found_so_far) > 0):
decrypted_str += chr(ord('a') +
(modulo_by_26(num_found_so_far)))
return decrypted_str
# Driver code
if __name__ == "__main__":
s = "32ytAAcV4ui30hf10hj18"
# Print the decrypted string
print(decrypt_message(s))
# This code is contributed by ChitranayalC#
// C# implementation of the approach
using System;
class GFG{
static int MOD = 26;
// Function that returns (num % 26)
static int modulo_by_26(String num)
{
// Initialize result
int res = 0;
// One by one process all digits of 'num'
for(int i = 0; i < num.Length; i++)
{
res = ((res * 10 +
(int)num[i] - '0') % MOD);
}
return res;
}
// Function to return the decrypted String
static String decrypt_message(String s)
{
// To store the readonly decrypted answer
String decrypted_str = "";
String num_found_so_far = "";
// One by one check for each character
// if it is a numeric character
for(int i = 0; i < s.Length; ++i)
{
if (s[i] >= '0' && s[i] <= '9')
{
num_found_so_far += s[i];
}
else if (num_found_so_far.Length > 0)
{
// Modulo the number found
// in the String by 26
decrypted_str += (char)('a' +
modulo_by_26(num_found_so_far));
num_found_so_far = "";
}
}
if (num_found_so_far.Length > 0)
{
decrypted_str += (char)('a' +
modulo_by_26(num_found_so_far));
}
return decrypted_str;
}
// Driver code
public static void Main(String[] args)
{
String s = "32ytAAcV4ui30hf10hj18";
// Print the decrypted string
Console.Write(decrypt_message(s));
}
}
// This code is contributed by amal kumar choubey输出：
geeks