Count characters with same neighbors in C++

We are given a string with, let’s say, str and the task is to compute the count of characters in a string str having the same neighbors and that will include both left and right side of a character in a string. Also, in this scenario the first and last character in a string will always be considered as they have only one adjacent character.

For Example

Input − string str = “poiot” Output − count is 3

Explanation − In the given string characters p, t and i are having the same neighbors so the count will be increased to 3.

Input − string str = “nitihig” Output − count is 4

Explanation − In the given string characters n, t, h and g are having the same neighbors so the count will be increased to 4.

Approach used in the below program is as follows

• Input the string in a variable let’s say str

• Calculate the length of string str using length() function that will return an integer value as per the number of letters in the string including the spaces.

• If the length of the string is less than or equals 2 then return the count as the length of the string because they all will be counted.

• If the length of the string is greater than 2, initialise the count with 2.

• Now, start the loop with i to 1 till i is less than (length-1)

• Inside the loop, check if (str[i-1] = str[i+1]) then increase the count by 1

• Now return the total value of count

• Print the result.

Example

 Live Demo

#include <iostream> using namespace std; // To count the characters int countChar(string st){    int size = st.length();    if (size <= 2){       return size;    }    int result = 2;    // Traverse the string    for (int i = 1; i < size - 1; i++){       // Increment the count by 1 if the previous       // and next character is same       if (st[i - 1] == st[i + 1]){          result++;       }    }    // Return result    return result; } int main(){    string st = "poiot";    cout <<"count is " <<countChar(st);    return 0; }

Output

If we run the above code it will generate the following output

count is 3