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September 8, 2020 19:59
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Find a quotient and a remainder without using division or modulo
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# Quotient and Remainder without using division | |
def divide (num, div): | |
low, high = 0, num | |
d = high - low | |
# Keep going until there's no more midpoints between high and low | |
# Need to find the value for x such that x*div ~ num | |
while d > 1: | |
# Calculate d here or there's one iteration too few | |
d = high - low | |
# Rshift kinda sorta halves the number | |
# Enough to find a midpoint | |
mid = low+(d>>1) | |
# Is the midpoint*div higher than the num? | |
# If so, x is between low and mid | |
# Otherwise x is between mid and high | |
if mid*div > num: | |
high = mid | |
else: | |
low = mid | |
return mid, num-mid*div | |
# Should print (3, 2) | |
# 3*3 == 9 | |
# 11-9 = 2 | |
print (divide (11,3)) |
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Basically a search for a number in a dataset - but what are we searching for?
Looking for a number n such that n*div is very close to num. Find the n that produces a number the closest to num without exceeding it and that's your answer