From 4ce99c998b6b77fce4b2590c17b921b3b76faa38 Mon Sep 17 00:00:00 2001
From: rizka10 <ristoe@hotmail.com>
Date: Thu, 3 Nov 2016 11:11:17 +0200
Subject: [PATCH] Improve summing poll percentages to 100

My first JavaScript! I have little experience with C++ and even less with Java, but that was enough to figure out a way to solve the task. The solution is rather good, but there may be better ways. I'm going to start a pull request. Even if it gets rejected, an expert can use the idea.

NOTE: The code needs some serious testing before potential merging. I did some testing and it worked, but don't trust in my skills.
---
 .../assets/javascripts/lib/even-round.js.es6  | 28 +++++++++++++------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/plugins/poll/assets/javascripts/lib/even-round.js.es6 b/plugins/poll/assets/javascripts/lib/even-round.js.es6
index 0395f1f16a6..5446c874c58 100644
--- a/plugins/poll/assets/javascripts/lib/even-round.js.es6
+++ b/plugins/poll/assets/javascripts/lib/even-round.js.es6
@@ -1,17 +1,29 @@
-// stolen from http://stackoverflow.com/a/13484088/11983
+// works as described on http://stackoverflow.com/a/13483710
 function sumsUpTo100(percentages) {
   return percentages.map(p => Math.floor(p)).reduce((a, b) => a + b) === 100;
 }
 
 export default (percentages) => {
-  const sumOfDecimals = Math.ceil(percentages.map(a => a % 1).reduce((a, b) => a + b));
-  // compensate error by adding 1 to the first n "non-zero" items
-  for (let i = 0, max = percentages.length; i < sumOfDecimals && i < max; i++) {
-    if (percentages[i] > 0) {
-      percentages[i] = ++percentages[i];
-      // quit early when there is a rounding issue
-      if (sumsUpTo100(percentages)) break;
+  var decimals = percentages.map(a => a % 1);
+  const sumOfDecimals = Math.ceil(decimals.reduce((a, b) => a + b));
+  // compensate error by adding 1 to n items with the greatest decimal part
+  for (let i = 0, max = decimals.length; i < sumOfDecimals && i < max; i++) {
+    // find the greatest item in the decimals array, set it to 0,
+    // and increase the corresponding item in the percentages array by 1
+    let greatest = 0;
+    let index = 0;
+    for (let j=0; j < decimals.length; j++) {
+      if (decimals[j] > greatest) {
+        index = j;
+        greatest = decimals[j];
+      }
     }
+    ++percentages[index];
+    decimals[index] = 0;
+    // quit early when there is a rounding issue
+    if (sumsUpTo100(percentages)) break;
   }
+
   return percentages.map(p => Math.floor(p));
 };
+