From e27ed7e95658c16f16d24e55e788947a359f3877 Mon Sep 17 00:00:00 2001
From: Kjetil Orbekk <kjetil.orbekk@gmail.com>
Date: Tue, 11 Aug 2015 11:00:28 -0400
Subject: Optimized C++ version.

---
 scheduling/scheduling.cc | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/scheduling/scheduling.cc b/scheduling/scheduling.cc
index bd1f6bb..6b03e31 100644
--- a/scheduling/scheduling.cc
+++ b/scheduling/scheduling.cc
@@ -91,7 +91,7 @@ template <typename GeneratorT>
 vector<std::tuple<string, string>> GenerateMatches(
     GeneratorT generator,
     vector<Player> players) {
-  std::list<std::tuple<int, int>> possible_matches;
+  std::vector<std::tuple<int, int>> possible_matches;
   for (int i = 0; i < players.size(); i++) {
     for (int j = 0; j < players.size(); j++) {
       // X vs. y and y vs. x is the same match. Also excludes x vs. x.
@@ -102,18 +102,13 @@ vector<std::tuple<string, string>> GenerateMatches(
       }
     }
   }
+  std::shuffle(possible_matches.begin(), possible_matches.end(),
+               generator);
 
   vector<std::tuple<string, string>> result;
-  while (!possible_matches.empty()) {
-    std::uniform_int_distribution<int> distribution(
-        0, possible_matches.size() - 1);
-    int i = distribution(generator);
-    auto it = possible_matches.begin();
-    std::advance(it, i);
-    Player* p1 = &players[std::get<0>(*it)];
-    Player* p2 = &players[std::get<1>(*it)];
-    possible_matches.erase(it);
-
+  for (const auto&m : possible_matches) {
+    Player* p1 = &players[std::get<0>(m)];
+    Player* p2 = &players[std::get<1>(m)];
     if (p1->desired_games_ && p2->desired_games_) {
       result.push_back(std::tuple<string, string>(p1->id_, p2->id_));
       p1->desired_games_--;
-- 
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