findMaxAverage

#sliding windows exercise. see video by


class Solution:
    def compressString(self, chars, k):
       
        #first run with n - k to obtain first sum
        #for i in range(n - k):
        window_sum = sum(chars[:k]) 
        #window_sum /= k
        maxSum = window_sum
        #no need for a two loop though having two loops does not
        #mean punishment in terms of performance. Only when they 
        #are nested
        #moving the window here
        for i in range(k, len(chars)):
            print(k, chars[k])
            #previous windows_sum was 2
            #so we recalculate window_sum
            # TRICKY CODE BELOW but it works like this: window_sum(prev val) + chars[i] (val added) - chars[i-k] (val removed)
            window_sum = window_sum + chars[i] - chars[i-k]
            maxSum = max(maxSum, window_sum)
        return maxSum / k
            #window_sum = current_sum + chars[i-k] + chars[i]
        
      
myVar = Solution()     
myVar.compressString([1, 12,  -5, -6, 50, 3], 4)