From 1eefd58ca4fdb5d2f51f657bfd70c9a89a4707db Mon Sep 17 00:00:00 2001
From: Iru Cai <mytbk920423@gmail.com>
Date: Thu, 24 May 2018 21:39:58 +0800
Subject: initial commit

---
 euler39.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 euler39.c

(limited to 'euler39.c')

diff --git a/euler39.c b/euler39.c
new file mode 100644
index 0000000..e4cd40c
--- /dev/null
+++ b/euler39.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+
+int np(int p)
+{
+	int n = 0;
+	int a;
+
+	/* p = a + b + c, with a*a+b*b=c*c */
+	/* b = (p*p-2pa)/(2p-2a) */
+	if (p % 2 == 1)
+		return 0;
+
+	a = 1;
+	while (1) {
+		int nu = p * (p - a*2);
+		int de = (p - a) * 2;
+		if (nu % de == 0 && nu/de > a)
+			n++;
+		if (nu/de < a)
+			break;
+		a++;
+	}
+	return n;
+}
+
+int main()
+{
+	int bestp, M = 0;
+	int i;
+	for (i = 3; i<=1000; i++) {
+		int m = np(i);
+		if (m > M) {
+			bestp = i;
+			M = m;
+		}
+	}
+	printf("%d\n", bestp);
+}
-- 
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