Use the Tracing Recursion: the box method to draw isPalindrome("racecar", 0, 7) for the follow code below.

bool isPalindrome(const string &str, int s, int e) { if (s >= e) { return true; } if (str[s] != str[e]) { return false; } return isPalindrome(str, s + 1, e - 1); }