QuickSort.Cpp

quicksort.cpp

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+/*
+Quick Sort 
+Avg Performance O(nlogn)
+Worst Performance O(n^2)
+Space Compexity O(logn)
+Not Stable
+*/
+
+#include<iostream>
+using namespace std;
+int partition(int a[],int l,int h)
+{
+    int i=l,j=h+1,pivot;
+    pivot=a[l];
+    while(i<=j)
+    {
+        do{
+            i++;
+        }while(a[i]<=pivot);
+        do{
+            j--;
+        }while(a[j]>pivot);
+        if(i<j){
+            swap(a[i],a[j]);
+        }
+    }
+    swap(a[l],a[j]);
+
+    return j;
+}
+void quicksort(int a[],int l,int h)
+{    if(l<h){
+        int t=partition(a,l,h);
+        quicksort(a,l,t-1);
+        quicksort(a,t+1,h);  
+    }
+}
+void swap(int &x,int &y)
+{
+    int t;t=x;x=y;y=t;
+}
+int main()
+{
+    int i,n;
+    cout<<"Enter the number of elements:- ";
+    cin>>n;
+    int a[n];
+    cout<<"Enter the Array elements:- ";
+    for(i=0;i<n;i++)
+    cin>>a[i];
+    quicksort(a,0,n-1);
+    cout<<"After sorting:- ";
+    for(i=0;i<n;i++)
+        cout<<a[i]<<" ";
+    cout<<endl;
+    return 0;
+}