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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
Here are the programs that implements the above algorithm −
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
// Function to count the number of ways to place characters alternately
int countWaysToPlaceAlternately(const char *s1, const char *s2) {
int len1 = strlen(s1);
int len2 = strlen(s2);
int diff = abs(len1 - len2); // Calculate the absolute difference in lengths
if (diff > 1) {
return 0; // If the difference is more than 1, it's not possible to place alternately
} else if (diff == 0) {
return 2; // If the lengths are equal, two ways to place alternately (s1s2 or s2s1)
} else {
return 1; // If the difference is 1, only one way to place alternately (the shorter string goes in the middle)
}
}
int main() {
const char *s1 = "abc";
const char *s2 = "de";
int ways = countWaysToPlaceAlternately(s1, s2); // Calculate the number of ways to place alternately
printf("The number of ways to place the characters alternately is: %d\n", ways);
return 0;
}
Output
The number of ways to place the characters alternately is: 1
#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
public class AlternatingPlacement {
// Function to count the number of ways to place characters alternately
static int countWaysToPlaceAlternately(String s1, String s2) {
int len1 = s1.length();
int len2 = s2.length();
int diff = Math.abs(len1 - len2); // Calculate the absolute difference in lengths
if (diff > 1) {
return 0; // If the difference is more than 1, it's not possible to place alternately
} else if (diff == 0) {
return 2; // If the lengths are equal, two ways to place alternately (s1s2 or s2s1)
} else {
return 1; // If the difference is 1, only one way to place alternately (the shorter string goes in the middle)
}
}
public static void main(String[] args) {
String s1 = "abc";
String s2 = "de";
int ways = countWaysToPlaceAlternately(s1, s2); // Calculate the number of ways to place alternately
System.out.println("The number of ways to place the characters alternately is: " + ways);
}
}
Output
The number of ways to place the characters alternately is: 1
def count_ways_to_place_alternately(s1, s2):
len1 = len(s1)
len2 = len(s2)
diff = abs(len1 - len2) # Calculate the absolute difference in lengths
if diff > 1:
return 0 # If the difference is more than 1, it's not possible to place alternately
elif diff == 0:
return 2 # If the lengths are equal, two ways to place alternately (s1s2 or s2s1)
else:
return 1 # If the difference is 1, only one way to place alternately (the shorter string goes in the middle)
def main():
s1 = "abc"
s2 = "de"
ways = count_ways_to_place_alternately(s1, s2) # Calculate the number of ways to place alternately
print("The number of ways to place the characters alternately is:", ways)
if __name__ == "__main__":
main()
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.
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