From f3688bbc7f03b3af6efc975a2f0c329263ad943d Mon Sep 17 00:00:00 2001
From: incredibleLeitman <michael.leithner@gmail.com>
Date: Tue, 6 Oct 2020 16:28:39 +0200
Subject: [PATCH] using size_t (uint32) instead of int because only use
 positive values

---
 MedianQuicksort.h | 26 +++++++++++---------------
 main.cpp          | 30 +++++++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/MedianQuicksort.h b/MedianQuicksort.h
index f6f5ec8..e743d19 100644
--- a/MedianQuicksort.h
+++ b/MedianQuicksort.h
@@ -1,10 +1,10 @@
 #pragma once
 
-int partition(std::vector<size_t>& values, int left, int right) {
-    int pivotIndex = left + (right - left) / 2;
-    int pivotValue = values[pivotIndex];
-    int i = left, j = right;
-    int temp;
+size_t pivotPartition(std::vector<size_t>& values, size_t left, size_t right) {
+    size_t pivotIndex = left + (right - left) / 2;
+    size_t pivotValue = values[pivotIndex];
+    size_t i = left;
+    size_t j = right;
     while (i <= j) {
         while (values[i] < pivotValue) {
             i++;
@@ -13,9 +13,7 @@ int partition(std::vector<size_t>& values, int left, int right) {
             j--;
         }
         if (i <= j) {
-            temp = values[i];
-            values[i] = values[j];
-            values[j] = temp;
+            std::swap(values[i], values[j]);
             i++;
             j--;
         }
@@ -23,18 +21,16 @@ int partition(std::vector<size_t>& values, int left, int right) {
     return i;
 }
 
-void quicksort(std::vector<size_t>& values, int left, int right) {
+void quicksort(std::vector<size_t>& values, size_t left, size_t right) {
     if (left < right) {
-        int pivotIndex = partition(values, left, right);
+        size_t pivotIndex = pivotPartition(values, left, right);
         quicksort(values, left, pivotIndex - 1);
         quicksort(values, pivotIndex, right);
     }
 }
 
-size_t getMedian(std::vector<size_t> values) {
-    //std::qsort(numbers); // only takes array param
+size_t getQuicksortMedian(std::vector<size_t> values, size_t i) {
+    //std::qsort(numbers); // only takes array param -> custom implementation with vector
     quicksort(values, 0, values.size() - 1);
-    size_t idxMed = values.size() / 2;
-    if (idxMed - (int)idxMed > 0) idxMed++;
-    return values[idxMed];
+    return values[i];
 }
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
index 12cfae1..161ff81 100644
--- a/main.cpp
+++ b/main.cpp
@@ -4,23 +4,43 @@
 #include "fileHandler.h"
 #include "Timing.h"
 #include "MedianQuicksort.h"
+#include "MedianOfMedians.h"
+#include "RandomizedSelect.h"
 
 int main(int argc, char** argv) {
+    // read test values from input file
     Timing::getInstance()->startRecord("init");
     std::vector<size_t> numbers = readFromFile("testdata");
-    std::cout << "read " << numbers.size() << " values" << std::endl;
+    std::cout << "just read " << numbers.size() << " values" << std::endl;
     Timing::getInstance()->stopRecord("init");
 
+    // index of median -> if odd count +1
+    size_t idxMed = numbers.size() / 2;
+    std::cout << "median =  " << idxMed << std::endl;
+    if (idxMed - (int)idxMed > 0) idxMed++;
+
     // vollständige Sortierung mit Quicksort und Ausgabe des mittleren Elements
     Timing::getInstance()->startRecord("quicksort");
-    std::cout << "quicksort median: " << getMedian(numbers) << std::endl;
+    std::cout << "quicksort median: " << getQuicksortMedian(numbers, idxMed) << std::endl;
     Timing::getInstance()->stopRecord("quicksort");
 
+    // vorgestellter Randomzized - Select rekursiv implementiert
+    Timing::getInstance()->startRecord("randomized select");
+    std::cout << "randomized select: " << randomizedSelect(numbers, 0, numbers.size() - 1, idxMed) << std::endl;
+    Timing::getInstance()->stopRecord("randomized select");
+
+    // ein weiterer Median - Algorithmus aus der Literatur
+    Timing::getInstance()->startRecord("median of medians");
+    std::cout << "median of medians: " << getMedianOfMedians(numbers, idxMed) << std::endl;
+    Timing::getInstance()->stopRecord("median of medians");
+
+    // noch ein ein weiterer Median - Algorithmus weil wir so cool sind
+    Timing::getInstance()->startRecord("wirth");
+    Timing::getInstance()->stopRecord("wirth");
+
     // Verwendung des C++ STL function templates nth_element
     Timing::getInstance()->startRecord("nth element");
-    std::nth_element(numbers.begin(), numbers.begin() + numbers.size() / 2, numbers.end());
-    size_t idxMed = numbers.size() / 2;
-    if (idxMed - (int)idxMed > 0) idxMed++;
+    std::nth_element(numbers.begin(), numbers.begin() + idxMed, numbers.end());
     std::cout << "nth element: " << numbers[idxMed] << std::endl;
     Timing::getInstance()->stopRecord("nth element");