BinarySearch

gistfile1.coffee

array = [1,4,5,6,10,13]

class BinarySearch 
    constructor:(@elems)->
        @len = @elems.length
        
    midPoint = (start, end)-> 
        ((end - start)/2) + start  
    
    find : (value, start=0, end =-1)-> 
        end = @len if end is -1 
        console.log 'start %s end %s', start, end 
        if end < start 
            return null 
        else 
           
            mid = midPoint start, end 
            console.log 'elems[%s] = %s', mid , @elems[mid]
            if mid is @len or mid is 0  
                return null 
            if @elems[mid] > value 
                console.log 'go left' 
                return @find(value, start, mid - 1)  
            else if @elems[mid] < value 
                console.log 'go right' 
                return @find( value, mid + 1, end) 
            else 
                mid 

result = new BinarySearch(array).find(4) 
console.log 'done'
console.log 'results %s', result