in c++ pls with an explanation!

Given a string the user enters (assume the user is benevolent and cannot produce an output that will error your code, that is to say worry about only [A...Za...z]) find the longest occurring substring using a divide and conquer approach. If multiple strings would be tied for the longest overall substring length return the earliest occurring string (relative to the original inputted string). Massive hint: An introduction of a character that makes a string not awesome would be a good partition for your string, you can form a string going from the left of the character until that character (omit that character) and you can form a string going from the right of the character (omit that character) until the end of the string. For example aBAbCeEfF would split into sequence: aBAb and eEff. These are both awesome strings, so pick aBAb since it occurs earlier in the inputted string