A string w of a's and b's is valid if it satisfies one of the following conditions: w is the empty string w = aub for some valid string u w = uv for some valid strings u and v For example, the string w = aaabbabbaabbab is valid, because w : = uv, where u = aaabbabb and v= aabbab.

Describe an efficient algorithm to determine whether a given string of a's and b's is valid. Analyze its time and space requirements. (Aim for solving the problem in linear time.) Show how the algorithm works on the above example.

No code please only algorithm