解密通过重复第 i 个字符i 次加密的字符串

给定一个加密字符串str和加密算法，任务是解密该字符串。加密算法如下：
字符串的^第一个字符将在加密字符串中重复一次，^第二个字符将重复两次，……，第n^个字符将重复n次。例如，字符串“abcd”将被加密为“abbcccdddd” 。

例子：

Input: str = “geeeeekkkksssss”
Output: geeks

Input: str = “abbcccdddd”
Output: abcd

编程需要懂一点英语

方法：初始化i = 0并打印str[i] 。
更新i = i + 1并打印str[i] ，然后在i < length(str)时更新i = i + 2并打印str[i]等等。

下面是上述方法的实现：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
// Function to return the decrypted string
string decryptString(string str, int n)
{
 
    // Initial jump will be 1
    int i = 0, jump = 1;
    string decryptedStr = "";
 
    while (i < n) {
        decryptedStr += str[i];
        i += jump;
 
        // Increment jump by 1 with every character
        jump++;
    }
 
    return decryptedStr;
}
 
// Driver code
int main()
{
    string str = "geeeeekkkksssss";
    int n = str.length();
    cout << decryptString(str, n);
 
    return 0;
}

Java

// Java implementation of the approach
class GFG
{
 
// Function to return the decrypted string
static String decryptString(String str, int n)
{
 
    // Initial jump will be 1
    int i = 0, jump = 1;
    String decryptedStr = "";
 
    while (i < n)
    {
        decryptedStr += str.charAt(i);
        i += jump;
 
        // Increment jump by 1 with every character
        jump++;
    }
 
    return decryptedStr;
}
 
// Driver code
public static void main(String[] args)
{
    String str = "geeeeekkkksssss";
    int n = str.length();
    System.out.println(decryptString(str, n));
}
}
 
// This code is contributed by Code_Mech

Python3

# Python 3 implementation of the approach
 
# Function to return the decrypted string
def decryptString(str, n):
     
    # Initial jump will be 1
    i = 0
    jump = 1
    decryptedStr = ""
 
    while (i < n):
        decryptedStr += str[i];
        i += jump
 
        # Increment jump by 1 with
        # every character
        jump += 1
 
    return decryptedStr
 
# Driver code
if __name__ == '__main__':
    str = "geeeeekkkksssss"
    n = len(str)
    print(decryptString(str, n))
 
# This code is contributed by
# Surendra_Gangwar

C#

// C# implementation of the approach
using System;
 
class GFG
{
 
// Function to return the decrypted string
static string decryptString(string str, int n)
{
 
    // Initial jump will be 1
    int i = 0, jump = 1;
    string decryptedStr = "";
 
    while (i < n)
    {
        decryptedStr += str[i];
        i += jump;
 
        // Increment jump by 1 with every character
        jump++;
    }
 
    return decryptedStr;
}
 
// Driver code
public static void Main()
{
    string str = "geeeeekkkksssss";
    int n = str.Length;
    Console.Write(decryptString(str, n));
}
}
 
// This code is contributed by ita_c

PHP

Javascript

输出：

geeks