def __select(self, left, right, check_value):
"""
:param left: lower index of the array.
:param right: higher index of the array.
:param check_value: the control value
"""
x = self.__median_of_medians(left, right)
"""
4.
Partition the array around the median of medians
"""
key = self.__partition(left, right, x)
# Add all the elements smaller or equal than the key (excluded)
partial_sum = sum_array(self.array[left:key])
"""
5.
If adding the key to the partial_sum
makes this greater than the target return the key,
else recursively select in relative subarray
"""
debug_lwm('median: {}'.format(self.array[key]))
if check_value > partial_sum >= check_value - self.array[key]:
return key
elif partial_sum == check_value:
return key - 1
elif partial_sum > check_value:
return self.__select(left, key, check_value)
else:
return self.__select(key, right, check_value - partial_sum)
def __median_of_5(self, left, right):
self.__insertion_sort(left, right)
median = (left + right) // 2
debug_lwm('md5[{}:{}] {} median: {}'.format(left, right,
self.array[left:right],
self.array[median]))
return median
def __duplicated_values(self, idx):
x = idx
while self.array[x] == self.array[x + 1]:
debug_lwm("{}\t{}".format(self.array[x], self.array[x + 1]))
x += 1
return idx, x
def __lwm_calculate(self, left, right, sumTarget): # check_value
med = (right - left) // 2
sommaTotale = self.sum_array
index = self.__select(left, right, med)
debug_lwm(index)
array_idx = self.__duplicated_values(index)
sumLeftPivot = self.__sum(self.array[0:array_idx[0]])
sumRightPivot = self.__sum(self.array[array_idx[1]:right + 1])
debug_lwm((sumLeftPivot, sumLeftPivot))
while not (sumLeftPivot < sumTarget and sumRightPivot <= sumTarget):
if sumLeftPivot >= sumTarget:
tmpRight = index
med = left + (tmpRight - left) / 2
index = self.__select(left, tmpRight, med)
array_idx = self.__duplicated_values(index)
sumRightPivot = sumRightPivot + self.__sum(
self.array[array_idx[1] + 1:tmpRight])
sumLeftPivot = sommaTotale - sumRightPivot - self.__sum(
self.array[array_idx[0]:array_idx[1]])
else:
tmpLeft = index
med = tmpLeft + (right - tmpLeft) / 2
index = self.__select(tmpLeft, right, med)
array_idx = self.__duplicated_values(index)
sumLeftPivot = sumLeftPivot + self.__sum(
self.array[tmpLeft:array_idx[0] - 1])
sumRightPivot = sommaTotale - sumLeftPivot - self.__sum(
self.array[array_idx[0]:array_idx[1]])
return index