#CodeChalenge AlgoExpert Longest palindrome in a string

LongestPalindrome.cpp

using namespace std;

vector<int> compareHelper(string str, int startIndex, int endIndex) {
	while (startIndex >= 0 && endIndex < str.size()) {
		if (str[startIndex] != str[endIndex]) {
			break;
		}
		startIndex--;
		endIndex++;
	}
	return { startIndex + 1, endIndex };
}

int getSize(vector<int>& vec) {
	return vec[1] - vec[0];
}

string longestPalindromicSubstring(string str) {
  vector<int> longest{0, 1};
	for (int i = 1; i < str.size(); i++) {
		vector<int> even = compareHelper(str, i - 1, i);
		vector<int> odd = compareHelper(str, i - 1, i + 1);
		vector<int> currentLong = getSize(even) > getSize(odd) ? even : odd;
		if (getSize(longest) < getSize(currentLong)) {
			longest = currentLong;
		}
	}
  return str.substr(longest[0], longest[1] - longest[0]);
}