project euler solution #32, in C and python

2 files changed, 141 insertions, 0 deletions

diff --git a/src/projecteuler/032.c b/src/projecteuler/032.c
new file mode 100644
index 0000000..13c40b5
--- /dev/null
+++ b/src/projecteuler/032.c
@@ -0,0 +1,64 @@
+
+#include <stdio.h>
+
+/*
+ * much faster than python version, though less optimized...
+ *
+ * to filter out duplicates and add numbers:
+ * $ ./032 | sort -u | tr "\n" "+" | sed 's/+$/\n/' | bc
+ *
+ */
+
+int is_pandigital(long int a, long int b, long int c)
+{
+	char digits[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+	char digit;
+	int i;
+
+	while(a > 0)
+	{
+		digit = a % 10;
+		if(digit == 0 || digits[digit]++)
+			return 0;
+		a /= 10;
+	}
+	while(b > 0)
+	{
+		digit = b % 10;
+		if(digit == 0 || digits[digit]++)
+			return 0;
+		b /= 10;
+	}
+	while(c > 0)
+	{
+		digit = c % 10;
+		if(digit == 0 || digits[digit]++)
+			return 0;
+		c /= 10;
+	}
+
+	for(i=1; i<10; i++)
+		if(digits[i] != 1)
+			return 0;
+	return 1;
+}
+
+int main(void)
+{
+	long int limit = 10000;
+	long int a, b, c;
+	for(a=2; a<limit; a++)
+	{
+		for(b=2; b<limit; b++)
+		{
+			c = a * b;
+			if(c > limit)
+				break;
+			if(is_pandigital(a, b, c))
+				printf("%ld\n", c);
+		}
+	}
+
+	return 0;
+}
+
diff --git a/src/projecteuler/032.py b/src/projecteuler/032.py
new file mode 100644
index 0000000..86b0956
--- /dev/null
+++ b/src/projecteuler/032.py
@@ -0,0 +1,77 @@
+
+digits = set()
+digits.add(1)
+digits.add(2)
+digits.add(3)
+digits.add(4)
+digits.add(5)
+digits.add(6)
+digits.add(7)
+digits.add(8)
+digits.add(9)
+
+pandigital = set()
+pandigital.add(1)
+pandigital.add(2)
+pandigital.add(3)
+pandigital.add(4)
+pandigital.add(5)
+pandigital.add(6)
+pandigital.add(7)
+pandigital.add(8)
+pandigital.add(9)
+
+# return digits that are not in x
+def missing(x):
+	d = set()
+	while x > 0:
+		d.add(x % 10)
+		x /= 10
+	return digits - d
+
+for i in range(2, 5):
+	new = set()
+	for x in pandigital:
+		for y in missing(x):
+			new.add(x*10 + y)
+	pandigital |= new
+pandigital.remove(1)
+
+
+def is_pandigital(a, b, c):
+	d = [0]*10
+	while a > 0:
+		digit = a % 10
+		if d[digit] > 0:
+			return False
+		d[digit] += 1
+		a /= 10
+	while b > 0:
+		digit = b % 10
+		if d[digit] > 0:
+			return False
+		d[digit] += 1
+		b /= 10
+	while c > 0:
+		digit = c % 10
+		if d[digit] > 0:
+			return False
+		d[digit] += 1
+		c /= 10
+	return d[1:] == [1]*9
+
+products = set()
+
+for a in pandigital:
+	for b in pandigital:
+		c = a * b
+		if c in pandigital and is_pandigital(a, b, c):
+			#print str(a), "*", str(b), "=", str(c)
+			products.add(c)
+
+sum = 0
+for p in products:
+	sum += p
+
+print sum
+