hw1: impl multiply, power of

hw1/BigNum.hs

@@ -63,7 +63,7 @@ bigSubtract' (x:xs) [] b = let d = x - b
                                   else d : bigSubtract' xs [] 0
 
 bigEq :: BigNum -> BigNum -> Bool
-bigEq x y = stripLeadingZeroes x == stripLeadingZeroes y
+bigEq x y = stripLeadingZeroes (reverse x) == stripLeadingZeroes (reverse y)
 
 bigDec :: BigNum -> BigNum
 bigDec x = bigSubtract x [1]
@@ -73,10 +73,25 @@ bigDec x = bigSubtract x [1]
 -- If you are having trouble finding a solution, write a helper method that
 -- multiplies a BigNum by an Int.
 bigMultiply :: BigNum -> BigNum -> BigNum
-bigMultiply _ _ = error "Your code here"
+bigMultiply x y = reverse $ stripLeadingZeroes $ reverse $ bigMultiply' x y
+
+bigMultiply' :: BigNum -> BigNum -> BigNum
+bigMultiply' _ [] = []
+bigMultiply' x (y:ys) = bigAdd (bigMultiplyBlock x y) (bigMultiply (0:x) ys)
+
+bigMultiplyBlock :: BigNum -> Block -> BigNum
+bigMultiplyBlock x y = bigMultiplyBlock' x y 0
+
+bigMultiplyBlock' :: BigNum -> Block -> Block -> BigNum
+bigMultiplyBlock' [] _ 0 = []
+bigMultiplyBlock' [] _ c = [c]
+bigMultiplyBlock' (x:xs) y c = let p = x * y + c
+                               in (p `mod` maxblock) : bigMultiplyBlock' xs y (p `div` maxblock)
 
 bigPowerOf :: BigNum -> BigNum -> BigNum
-bigPowerOf _ _ = error "Your code here"
+bigPowerOf x [0] = [1]
+bigPowerOf x [1] = x
+bigPowerOf x y = bigMultiply x (bigPowerOf x (bigDec y))
 
 prettyPrint :: BigNum -> String
 prettyPrint [] = ""

hw1/output

@@ -10,4 +10,17 @@ Subtraction
 [1]
 [0]
 Multiplication
+[12]
+[0]
+[392,296,4,12]
+[518,250,645,161,37,915,479,1]
+Power Of
+[256]
+[1]
+Others
 7
+63
+256
+800,000,000,000,000,000,002
+1
+59,745,672,527,794,294,248,045