Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Rearrange an array such that arr[i] = i in C++
We are given a positive integer type array, let's say, arr[] of any given size such that elements in an array should value greater than 0 but less than the size of an array. The task is to rearrange an array in such a manner that if arr[i] is ‘i’, if ‘i’ is present in an array else it will set the arr[i] element with the value -1 and print the final result.
Let us see various input output scenarios for this −
Input − int arr[] = {0, 8, 1, 5, 4, 3, 2, 9 }
Output − Rearrangement of an array such that arr[i] = i is: 0 1 2 3 4 5 -1 -1
Explanation − we are given an integer array of size 8 and all the elements in an array value less than 8. Now, we will rearrange the array i.e.
arr[0] = 0(present in an array) arr[1] = 1(present in an array) arr[2] = 2(present in an array) arr[3] = 3(present in an array) arr[4] = 4(present in an array) arr[5] = 5(present in an array) arr[6] = -1(NOT present in an array) arr[7] = -1(NOT present in an array)
Input − int arr[] = {1, 2, 6, 9, 10}
Output − Rearrangement of an array such that arr[i] = i is: -1 1 2 -1 -1
Explanation − we are given an integer array of size 5 and all the elements in an array value less than 5. Now, we will rearrange the array i.e.
arr[0] = -1(NOT present in an array) arr[1] = 1(present in an array) arr[2] = 2(present in an array) arr[3] = -1(NOT present in an array) arr[4] = -1(NOT present in an array)
Approach used in the below program is as follows
Input an array of integer type elements and calculate the size of an array.
Print the array before arrangement and call the function Rearranging(arr, size)
Inside the function Rearranging(arr, size)
Declare an integer type variable let’s say, ptr
Start loop FOR from i to 0 till i less than size. Inside the loop, start another loop FOR from j to 0 till j less than size.
Inside the loop, check IF arr[j] = i then set ptr = arr[j], arr[j] to arr[i],arr[i] to ptr and break.
Start loop FOR from i to till i is less than size. Inside the loop, check IF arr[i]!=i then set arr[i] to -1.
Print the array after the rearrangement of values of an array.
Example
#include <iostream>
using namespace std;
void Rearranging(int arr[], int size){
int ptr;
for(int i = 0; i < size; i++){
for(int j = 0; j < size; j++){
if(arr[j] == i){
ptr = arr[j];
arr[j] = arr[i];
arr[i] = ptr;
break;
}
}
}
for(int i = 0; i < size; i++){
if(arr[i] != i){
arr[i] = -1;
}
}
}
int main(){
int arr[] = {0, 8, 1, 5, 4, 3, 2, 9 };
int size = sizeof(arr) / sizeof(arr[0]);
//calling the function to rearrange an array such that arr[i] = i
Rearranging(arr, size);
//Printing the array
cout<<"Rearrangement of an array such that arr[i] = i is: ";
for(int i = 0; i < size; i++){
cout << arr[i] << " ";
}
}Output
If we run the above code it will generate the following Output
Rearrangement of an array such that arr[i] = i is: 0 1 2 3 4 5 -1 -1
261 Views
