From 0d2341999a9c844954aca9ed4cc739b8fde34584 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <dcariotti24@gmail.com>
Date: Sun, 10 May 2020 18:57:13 +0200
Subject: chore: move algorithms file into self directory

---
 I_anno/Programmazione_2/algorithms/mergesort.cc | 52 +++++++++++++++++++++++++
 I_anno/Programmazione_2/algorithms/quicksort.cc | 38 ++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 I_anno/Programmazione_2/algorithms/mergesort.cc
 create mode 100644 I_anno/Programmazione_2/algorithms/quicksort.cc

(limited to 'I_anno/Programmazione_2/algorithms')

diff --git a/I_anno/Programmazione_2/algorithms/mergesort.cc b/I_anno/Programmazione_2/algorithms/mergesort.cc
new file mode 100644
index 0000000..68d28cb
--- /dev/null
+++ b/I_anno/Programmazione_2/algorithms/mergesort.cc
@@ -0,0 +1,52 @@
+#include<iostream>
+
+using namespace std;
+
+void merge(int A[], int l, int q, int r) {
+    int i = l;
+    int j = q+1;
+    int k = l;
+    int B[r];
+
+    while((i <= q) && (j <= r)) {
+        if(A[i] <= A[j])
+            B[k] = A[i++];
+        else
+            B[k] = A[j++];
+
+        k++;
+    }
+
+    while(i <= q)
+        B[k++] = A[i++];
+
+    while(j <= r)
+        B[k++] = A[j++];
+
+    for(k = l; k <= r; ++k) 
+        A[k] = B[k];
+}
+
+void mergesort(int A[], int l, int r) {
+    if(l < r) {
+        int q = (l+r)/2;
+        mergesort(A, l, q);
+        mergesort(A, q+1, r);
+        merge(A, l, q, 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;
+    mergesort(a, 0, 8);
+    for(int i = 0; i < 9; ++i) {
+        cout << a[i] << ' ';
+    }
+
+    return 0;
+}
diff --git a/I_anno/Programmazione_2/algorithms/quicksort.cc b/I_anno/Programmazione_2/algorithms/quicksort.cc
new file mode 100644
index 0000000..a646840
--- /dev/null
+++ b/I_anno/Programmazione_2/algorithms/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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