1 files changed, 27 insertions, 0 deletions
diff --git a/euler206.c b/euler206.c
new file mode 100644
index 0000000..2a5b007
--- /dev/null
+++ b/euler206.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+int test(long long t)
+{
+	t = t * t;
+	int b = 9;
+	while (b >= 1) {
+		if (t % 10 != b)
+			return 0;
+		b--;
+		t = t / 100;
+	}
+	return 1;
+}
+
+int main()
+{
+	/* test 1{0000000..5000000}{30,70} */
+	for (long long i = 10000000; i < 15000000; i++) {
+		long long t = i * 10 + 3;
+		if (test(t))
+			printf("%lld0\n", t);
+		t = i * 10 + 7;
+		if (test(t))
+			printf("%lld0\n", t);
+	}
+}