# Count ways to place all the characters of two given strings alternately

In this article, we will examine the concept of counting the ways to place all characters of two given strings alternately. This problem can appear in programming challenges and interviews, and mastering the solution will help you improve your string manipulation and algorithm skills. We will explain the problem statement, discuss the algorithm used, present the C++ implementation, and provide a test case example to illustrate the solution.

## Problem Statement

Given two strings s1 and s2, find the number of ways to place all the characters of both strings alternately, such that the characters from s1 and s2 are placed alternatively in the final string.

## Algorithm

• Check the length of both strings.

• If the difference in length between the two strings is greater than 1, return 0, as it is not possible to arrange the characters alternately.

• If the lengths of the strings are equal, the result will be 2, as you can start with either s1 or s2.

• If the length difference is exactly 1, the result will be 1, as you can only start with the longer string.

## C++ Implementation

### Example

#include <iostream>
#include <string>
#include <cstdlib>

int countWaysToPlaceAlternately(const std::string &s1, const std::string &s2) {
int len1 = s1.length();
int len2 = s2.length();
int diff = abs(len1 - len2);

if (diff > 1) {
return 0;
} else if (diff == 0) {
return 2;
} else {
return 1;
}
}

int main() {
std::string s1 = "abc";
std::string s2 = "de";

int ways = countWaysToPlaceAlternately(s1, s2);
std::cout << "The number of ways to place the characters alternately is: " << ways << std::endl;

return 0;
}


### Output

The number of ways to place the characters alternately is: 1


## Test Case Example

Let's consider the following example −

• String 1: "abc"

• String 2: "de"

Since the length difference between the two strings is 1, there is only one way to place the characters alternately, which is starting with the longer string (string 1). The final arrangement will be "adbec".

## Conclusion

In this article, we explored the problem of counting the ways to place all characters of two given strings alternately. We discussed the algorithm, presented the C++ implementation, and provided a test case example to demonstrate the solution. Mastering this problem helps improve your string manipulation and algorithm skills, which are vital for programming challenges and interviews. Make sure to compare the lengths of the input strings and handle different cases accordingly to achieve the correct results.

Updated on: 17-May-2023

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