Create Rearrange an array with O(1) extra space.cpp

Author: Amruta-26

arrays/c++/Rearrange an array with O(1) extra space.cpp

@@ -0,0 +1,90 @@
+/* Problem Statement -:
+Given an array arr[] of size N where every element is in the range from 0 to n-1. Rearrange the given array so that arr[i] becomes arr[arr[i]].
+ 
+Example 1:
+Input:
+N = 2
+arr[] = {1,0}
+Output: 0 1
+Explanation: 
+arr[arr[0]] = arr[1] = 0.
+arr[arr[1]] = arr[0] = 1.
+ 
+Example 2:
+Input:
+N = 5
+arr[] = {4,0,2,1,3}
+Output: 3 4 2 0 1
+Explanation: 
+arr[arr[0]] = arr[4] = 3.
+arr[arr[1]] = arr[0] = 4.
+and so on.
+ 
+Your Task:
+You don't need to read input or print anything. The task is to complete the function arrange() which takes arr and N as input parameters and rearranges the elements in the array in-place. 
+ 
+Expected Time Complexity: O(N)
+Expected Auxiliary Space: O(1)
+ 
+Constraints:
+1 <= N <= 107
+0 <= Arr[i] < N  */
+
+//Solution -:
+#include<bits/stdc++.h>
+using namespace std;
+
+
+ // } Driver Code Ends
+    
+
+class Solution{
+    public:
+    // arr: input array
+    // n: size of array
+    //Function to rearrange an array so that arr[i] becomes arr[arr[i]]
+    //with O(1) extra space.
+    void arrange(long long arr[], int n) {
+        // Your code here
+        long long brr[n];
+        for(int i=0;i<n;i++){
+            brr[i]=arr[i];
+        }
+        for(int i=0;i<n;i++){
+            arr[i]=brr[brr[i]];
+        }
+        
+    }
+};
+
+
+// { Driver Code Starts.
+
+int main(){
+    
+    int t;
+    //testcases
+    cin>>t;
+    while(t--){
+        
+        int n;
+        //size of array
+        cin>>n;
+        long long A[n];
+        
+        //adding elements to the array
+        for(int i=0;i<n;i++){
+            cin>>A[i];
+        }
+        Solution ob;
+        //calling arrange() function
+        ob.arrange(A, n);
+        
+        //printing the elements 
+        for(int i=0;i<n;i++){
+            cout << A[i]<<" ";
+        }
+        cout<<endl;
+    }
+    return 0;
+}  // } Driver Code Ends