From 3c4d885ba7fd25731c030813888b6e3285ed7c2a Mon Sep 17 00:00:00 2001
From: Charles Cabergs <me@cacharle.xyz>
Date: Fri, 15 Jan 2021 13:45:26 +0100
Subject: problem 206 in c

---
 c/206-concealed_square.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 c/206-concealed_square.c

(limited to 'c')

diff --git a/c/206-concealed_square.c b/c/206-concealed_square.c
new file mode 100644
index 0000000..4b94486
--- /dev/null
+++ b/c/206-concealed_square.c
@@ -0,0 +1,41 @@
+/*
+* Concealed Square
+* Problem 206
+*
+* Find the unique positive integer whose square has the form 1_2_3_4_5_6_7_8_9_0, where each “_” is a single digit.
+*/
+
+#include <stdio.h>
+#include <math.h>
+#include <stdbool.h>
+
+typedef long long unsigned int t_llu;
+
+int main(void)
+{
+	t_llu n = (t_llu)floor(sqrt(1020304050607080900)) - 1000;
+
+	while (true)
+	{
+		t_llu s = n * n;
+
+		if ((s % 10llu)                   / 1llu                   == 0 &&
+			(s % 1000llu)                 / 100llu                 == 9 &&
+			(s % 100000llu)               / 10000llu               == 8 &&
+			(s % 10000000llu)             / 1000000llu             == 7 &&
+			(s % 1000000000llu)           / 100000000llu           == 6 &&
+			(s % 100000000000llu)         / 10000000000llu         == 5 &&
+			(s % 10000000000000llu)       / 1000000000000llu       == 4 &&
+			(s % 1000000000000000llu)     / 100000000000000llu     == 3 &&
+			(s % 100000000000000000llu)   / 10000000000000000llu   == 2 &&
+			(s % 10000000000000000000llu) / 1000000000000000000llu == 1)
+		{
+			printf("%llu\n", n);
+			printf("%llu\n", s);
+			break;
+		}
+		n++;
+	}
+
+	return 0;
+}
-- 
cgit