3 Questions, 105 min (I finished in 45 min)\n\n1. given a string consisting of letters \'a\' and \'b\', output whether it\'s valid, a valid string means all occurrences of \'a\' happens before all occurrences of \'b\'\n2. same question as this one: https://www.chegg.com/homework-help/questions-and-answers/jimmy-owns-garden-planted-n-trees-row-years-trees-grown-different-heights-jimmy-pays-much--q45112705\n3. same as this one: https://brainly.com/question/15405872?exp=10-2

3 Questions, 105 min (I finished in 45 min)\n\n1. given a string consisting of letters \'a\' and \'b\', output whether it\'s valid, a valid string means all occ