76 lines
1.5 KiB
Python
76 lines
1.5 KiB
Python
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def equalize_strings(x, y):
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n = len(x)
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m = len(y)
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zeros = abs(n - m) * '0'
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if n > m:
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y = zeros + y
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elif m > n:
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x = zeros + x
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return x, y, len(x)
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def sum(x, y):
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x, y, size = equalize_strings(x, y)
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carry = 0
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result = ''
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for i in range(1, size+1):
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# print(i)
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dgt1 = int(x[size - i])
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dgt2 = int(y[size - i])
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dgt3 = (dgt1 + dgt2 + carry) % 10
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result = str(dgt3) + result
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carry = int((dgt1 + dgt2 + carry) / 10)
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# print(dgt1, dgt2, dgt3, result, carry)
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if carry:
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result = '1' + result
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return result
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def subtract(x, y):
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x, y, size = equalize_strings(x, y)
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carry = 0
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result = ""
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for i in range(size):
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if y[i] < x[i]:
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break
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elif x[i] < y[i]:
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tmp = x
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x = y
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y = tmp
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break
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for i in range(1, size+1):
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dgt1 = int(x[size - i])
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dgt2 = int(y[size - i])
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dgt3 = dgt1 - dgt2 - carry
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if dgt3 < 0:
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dgt3 += 10
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carry = 1
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else:
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carry = 0
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result = str(dgt3) + result
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return result
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def kmul(x ,y):
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x, y, size = equalize_strings(x, y)
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if size == 1:
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return str(int(x) * int(y))
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mid = int(size / 2)
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a = x[:mid]
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b = x[mid:]
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c = y[:mid]
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d = y[mid:]
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ac = kmul(a, c)
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bd = kmul(b, d)
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ab_cd = kmul(sum(a, b), sum(c, d))
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ad_bc = subtract(ab_cd, sum(ac, bd))
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zeros = "0" * (size - mid)
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result = sum(ac + 2 * zeros, ad_bc + zeros)
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result = sum(result, bd)
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result = result.lstrip('0')
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return result
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x = "134231412"
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y = "141324"
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print(kmul(x, y))
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