Trouble understanding a part of an algorithm - c++14

Question

The problem is to find special strings
A string is said to be a special string if either of two conditions is met:
All of the characters are the same, e.g. aaa.
All characters except the middle one are the same, e.g. aadaa.
This is the code I got and I understand the two cases.
Case 1: All Palindromic substrings have the same character
Case 2:Count all odd length Special Palindromic substrings with the
the middle character is different.
What I cannot understand is why I have to delete n from the result, I don't see where I am adding the extra 'n' in the algorithm.
int CountSpecialPalindrome(string str)
{
int n = str.length();
int result = 0;
int sameChar[n] = { 0 };
int i = 0;
// traverse string character from left to right
while (i < n) {
// store same character count
int sameCharCount = 1;
int j = i + 1;
// count smiler character
while (str[i] == str[j] && j < n)
sameCharCount++, j++;
// Case : 1
// so total number of substring that we can
// generate are : K *( K + 1 ) / 2
// here K is sameCharCount
result += (sameCharCount * (sameCharCount + 1) / 2);
// store current same char count in sameChar[]
// array
sameChar[i] = sameCharCount;
// increment i
i = j;
}
// Case 2: Count all odd length Special Palindromic
// substring
for (int j = 1; j < n; j++)
{
// if current character is equal to previous
// one then we assign Previous same character
// count to current one
if (str[j] == str[j - 1])
sameChar[j] = sameChar[j - 1];
// case 2: odd length
if (j > 0 && j < (n - 1) &&
(str[j - 1] == str[j + 1] &&
str[j] != str[j - 1]))
result += min(sameChar[j - 1],
sameChar[j + 1]);
}
// subtract all single length substring
return result - n;
}
// driver program to test above fun
int main()
{
string str = "abccba";
cout << CountSpecialPalindrome(str) << endl;
return 0;
}