"""
Example: 57 * 18
57 18
Halving the first column:
28 18
14
7
3
1
Doubling the second column:
28 36
14 72
7 144
3 288
1 576
Remove rows whose first cell is even:
18
28 36 x
14 72 x
7 144
3 288
1 576
Sum the remaining numbers in the right-hand column:
18
28 -
14 -
7 162
3 288
1 576
====
1026
"""
def ethiopianMultiply(a, b):
sum = 0
while a > 0:
if a % 2 == 1: # keep only odd rows
sum += b
print("sum =", sum)
a //= 2 # halve left side
b *= 2 # double right side
print("a =", a, "b =", b)
return sum
def main():
a = 57
b = 18
print(ethiopianMultiply(a, b))
if __name__ == "__main__":
main()
"""
run:
sum = 18
a = 28 b = 36
a = 14 b = 72
a = 7 b = 144
sum = 162
a = 3 b = 288
sum = 450
a = 1 b = 576
sum = 1026
a = 0 b = 1152
1026
"""
