From 88f415f0ae4dea98c759be211e95db4c3396cf50 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <dcariotti24@gmail.com>
Date: Thu, 26 Mar 2020 23:55:20 +0100
Subject: feat: quicksort algorithm

---
 I_anno/Programmazione_2/quicksort.cc | 38 ++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 I_anno/Programmazione_2/quicksort.cc

diff --git a/I_anno/Programmazione_2/quicksort.cc b/I_anno/Programmazione_2/quicksort.cc
new file mode 100644
index 0000000..a646840
--- /dev/null
+++ b/I_anno/Programmazione_2/quicksort.cc
@@ -0,0 +1,38 @@
+#include<iostream>
+
+using namespace std;
+
+int partition(int A[], int l, int r) {
+    int x = A[r];
+    int i = l-1;
+
+    for(int j = l; j < r; ++j) {
+        if(A[j] <= x) {
+            swap(A[++i], A[j]);
+        }
+    }
+    swap(A[++i], A[r]);
+    return i;
+}
+
+void quicksort(int A[], int l, int r) {
+    if(l < r) {
+        int q = partition(A, l, r);
+        quicksort(A, l, q-1);
+        quicksort(A, q+1, r);
+    }
+}
+
+int main() {
+    int a[] = {7,1,22,3,2,12,27,31,6};
+    for(int i = 0; i < 9; ++i) {
+        cout << a[i] << ' ';
+    }
+    cout << endl;
+    quicksort(a, 0, 9);
+    for(int i = 0; i < 9; ++i) {
+        cout << a[i] << ' ';
+    }
+
+    return 0;
+}
-- 
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