From 3e2770d6c01b40d5c72e5308779df39e2476514c Mon Sep 17 00:00:00 2001
From: Project Nayuki <me@nayuki.io>
Date: Sun, 26 Aug 2018 03:53:36 +0000
Subject: [PATCH] Somewhat simplified black/white balance penalty calculation.

---
 src/io/nayuki/fastqrcodegen/QrCode.java | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/io/nayuki/fastqrcodegen/QrCode.java b/src/io/nayuki/fastqrcodegen/QrCode.java
index a4d623f..797d59e 100644
--- a/src/io/nayuki/fastqrcodegen/QrCode.java
+++ b/src/io/nayuki/fastqrcodegen/QrCode.java
@@ -436,10 +436,10 @@ public final class QrCode {
 		}
 		
 		// Balance of black and white modules
-		int total = size * size;
-		// Find smallest k such that (45-5k)% <= dark/total <= (55+5k)%
-		for (int k = 0; black*20 < (9-k)*total || black*20 > (11+k)*total; k++)
-			result += PENALTY_N4;
+		int total = size * size;  // Note that size is odd, so black/total != 1/2
+		// Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)%
+		int k = (Math.abs(black * 20 - total * 10) + total - 1) / total - 1;
+		result += k * PENALTY_N4;
 		return result;
 	}