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@mfukar
Created May 26, 2016
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What would you like to do?
Some interview question from VMware. Figure out the problem statement, it's obvious.
import sys
def main():
N = raw_input()
elements = [int(element) for element in sys.stdin.read().split(' ')]
L, R = 0, len(elements)
# We got ourselves a maximum subarray problem, with inverted semantics.
# The subarray we want to find is the one to flip all the bits in.
# We will consider zero bits as having value of -1, and one bits as having value of 1.
# Then we modify Kadane's algorithm to search for largest negative sum instead of positive:
max_difference = 0
flip_start, flip_end = -1, -1
ones_to_flip = 0
total_ones = 0
current_difference = 0
current_start = 0
current_ones_to_flip = 0
for idx in range(L, R):
if elements[idx] == 0:
current_difference -= 1
else:
current_difference += 1
current_ones_to_flip += 1
total_ones += 1
if current_difference < max_difference:
max_difference = current_difference
flip_start = current_start
flip_end = idx
ones_to_flip = current_ones_to_flip
elif current_difference > 0:
current_difference = 0
current_start = idx + 1
current_ones_to_flip = 0
# The total number of 1-bits is the number of 1-bits in the flipped range, plus the
# number of 1-bits in the initial sequence minus those which will be flipped:
if flip_end != -1:
print(flip_end - flip_start + 1 - ones_to_flip + total_ones - ones_to_flip)
else:
print(total_ones)
main()
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