Lists-CompanionPlants2.cls

/*
Some plants are considered companion plants. They grow better when planted next to each other. For the purpose of this problem, we consider the following plants to be companions: lettuce and cucumbers, lettuce and onions, onions and carrots, and onions and tomatoes. The same plants planted next to each other are not considered companions.

Write a function isCompanion that takes as input a list of plants being planted in a row. Return true only if every plant in the list is planted next to a companion and return false otherwise.

companionPlants(new List { 'onions', 'lettuce', 'onions', 'carrots', 'onions', 'lettuce', 'cucumbers'}) = true

companionPlants(new List { 'lettuce', 'onions', 'carrots', 'lettuce', 'cucumbers'}) = false. We have non-companion plants carrots and lettuce planted together
*/
public Boolean companionPlants(List<String> plants) {
    //code here
    if(plants.size()==1){
        return False;
    }
    for(Integer i=0;i<plants.size()-1;i++){
        if (plants[i]=='lettuce' && !(plants[i+1] !='cucumbers' && plants[i+1] !='onions')){
            return False;
        }
        else if (plants[i]=='cucumbers' && plants[i+1] !='lettuce'){
            return False;
        }
        else if (plants[i]=='onions' && !(plants[i+1] !='lettuce' && plants[i+1] !='carrots' && plants[i+1] !='tomatoes')){
            return False;
        }
        else if (plants[i]=='carrots' && plants[i+1] !='onions'){
            return False;
        }
        else if (plants[i]=='tomatoes' && plants[i+1] !='onions'){
            return False;
        }

    }
    return True;
}