Add C solution for problem 32

problem-32.c

@@ -0,0 +1,124 @@
+#include<stdio.h>
+#include<stdlib.h>
+
+#define MAX_NUM 9999
+
+typedef struct Node {
+	int data;
+	struct Node* next;
+} Node;
+
+
+Node* create(int data, Node* node)
+{
+	Node* new = (Node*)malloc(sizeof(Node));
+	if (new == NULL) {
+		printf("Error allocating memory\n");
+		exit(1);
+	}
+
+	new->data = data;
+	new->next = node;
+	return new;
+}
+
+
+Node* prepend(Node* head, int data)
+{
+	return create(data, head);
+}
+
+
+int contains(Node* head, int data)
+{
+	Node* cursor = head;
+
+	while (cursor != NULL) {
+		if (cursor->data == data)
+			return 1;
+		cursor = cursor->next;
+	}
+
+	return 0;
+}
+
+
+int sum(Node* head)
+{
+	int total = 0;
+	Node* cursor = head;
+
+	while (cursor != NULL) {
+		total += cursor->data;
+		cursor = cursor->next;
+	}
+
+	return total;
+}
+
+
+int countDigits(long num)
+{
+	int count = 0;
+
+	while (num != 0) {
+		count++;
+		num /= 10;
+	}
+
+	return count;
+}
+
+
+int isNineDigits(int i, int j)
+{
+	return 9 == countDigits(i) + countDigits(j) + countDigits(i*j);
+}
+
+
+int isNinePandigital(int i, int j)
+{
+	int rem;
+	int digits = 0;
+	int prod = i*j;
+
+	if (!(isNineDigits(i, j)))
+		return 0;
+
+	while (i>0) {
+		rem = i % 10;
+		digits ^= 1 << rem;
+		i /= 10;
+	}
+
+	while (j>0) {
+		rem = j % 10;
+		digits ^= 1 << rem;
+		j /= 10;
+	}
+
+	while (prod>0) {
+		rem = prod % 10;
+		digits ^= 1 << rem;
+		prod /= 10;
+	}
+
+	return digits == 1022; /* 1022 == 1111111110 in binary */
+}
+
+
+int main(int argc, char** argv)
+{
+	int i, j;
+	int sumProds;
+	Node* pandigitals = NULL;
+
+	for (i=1; i<MAX_NUM; i++)
+		for (j=1; j<MAX_NUM; j++)
+			if (isNinePandigital(i, j) && !contains(pandigitals, i*j))
+				pandigitals = prepend(pandigitals, i*j);
+
+	sumProds = sum(pandigitals);
+	printf("The sum of the nine pandigital products is %d\n", sumProds);
+	return 0;
+}