Add solution for problem-59 and a C solution for problem 40

problem-40.c

@@ -0,0 +1,65 @@
+#include<stdlib.h>
+#include<stdio.h>
+#include<string.h>
+
+#define MAX_NUM 1000000
+
+char* LETTERS = "0123456789";
+
+
+int digits(int* res, int num)
+{
+	int len = 0;
+	while (num > 0) {
+		len++;
+		res = (int*)realloc(res, len * sizeof(int));
+		res[len-1] = num % 10;
+		num /= 10;
+	}
+
+	return len;
+}
+
+
+int main(int argc, char** argv)
+{
+	char* str;
+	int* digs;
+	int nums, j, result;
+	int digit = 0, i = 0, num = 1;
+
+	str = malloc(MAX_NUM * sizeof(int));
+	digs = malloc(0 * sizeof(int));
+	nums = digits(digs, num);
+
+	while (digit < MAX_NUM) {
+		str[digit] = digs[nums-1-i];
+		digit++;
+		i++;
+		if (i == nums) {
+			/* refill digs and reset i */
+			num++;
+			nums = digits(digs, num);
+			i = 0;
+			/* DEBUG
+			printf("num = %d str = ", num);
+			for (j=0; j<digit; j++)
+				printf("%d", str[j]);
+			printf("\n");
+			*/
+		}
+	}
+
+	result = str[0] *
+		str[9] *
+		str[99] *
+		str[999] *
+		str[9999] *
+		str[99999] *
+		str[999999];
+
+	printf("The result is %d\n", result);
+	return 0;
+}
+
+