Search, insert and delete in an unsorted array
In this post search, insert, and delete operations in an unsorted array are discussed.
Search Operation

In an unsorted array, the search operation can be performed by linear traversal from the first element to the last element.
C++
// C++ program to implement linear // search in unsorted array #include<bits/stdc++.h> using namespace std; // Function to implement search operation int findElement( int arr[], int n, int key) { int i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Driver Code int main() { int arr[] = {12, 34, 10, 6, 40}; int n = sizeof (arr) / sizeof (arr[0]); // Using a last element as search element int key = 40; int position = findElement(arr, n, key); if (position == - 1) cout << "Element not found" ; else cout << "Element Found at Position: " << position + 1; return 0; } // This code is contributed // by Akanksha Rai |
C
// C program to implement linear // search in unsorted array #include<stdio.h> // Function to implement search operation int findElement( int arr[], int n, int key) { int i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Driver Code int main() { int arr[] = {12, 34, 10, 6, 40}; int n = sizeof (arr) / sizeof (arr[0]); // Using a last element as search element int key = 40; int position = findElement(arr, n, key); if (position == - 1) printf ( "Element not found" ); else printf ( "Element Found at Position: %d" , position + 1 ); return 0; } |
Java
// Java program to implement linear // search in unsorted arrays class Main { // Function to implement // search operation static int findElement( int arr[], int n, int key) { for ( int i = 0 ; i < n; i++) if (arr[i] == key) return i; return - 1 ; } // Driver Code public static void main(String args[]) { int arr[] = { 12 , 34 , 10 , 6 , 40 }; int n = arr.length; // Using a last element as search element int key = 40 ; int position = findElement(arr, n, key); if (position == - 1 ) System.out.println( "Element not found" ); else System.out.println( "Element Found at Position: " + (position + 1 )); } } |
Python3
# Python program for searching in # unsorted array def findElement(arr, n, key): for i in range (n): if (arr[i] = = key): return i return - 1 arr = [ 12 , 34 , 10 , 6 , 40 ] key = 40 n = len (arr) #search operation index = findElement(arr, n, key) if index ! = - 1 : print ( "Element Found at position: " + str (index + 1 )) else : print ( "Element not found" ) # Thanks to Aditi Sharma for contributing # this code |
C#
// C# program to implement linear // search in unsorted arrays using System; class main { // Function to implement // search operation static int findElement( int []arr, int n, int key) { for ( int i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Driver Code public static void Main() { int []arr = {12, 34, 10, 6, 40}; int n = arr.Length; // Using a last element as // search element int key =40; int position = findElement(arr,n,key); if (position == - 1) Console.WriteLine( "Element not found" ); else Console.WriteLine( "Element Found at Position: " + (position+1)); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to implement linear // search in unsorted array // Function to implement // search operation function findElement( $arr , $n , $key ) { $i ; for ( $i = 0; $i < $n ; $i ++) if ( $arr [ $i ] == $key ) return $i ; return -1; } // Driver Code $arr = array (12, 34, 10, 6, 40); $n = sizeof( $arr ); // Using a last element // as search element $key = 40; $position = findElement( $arr , $n , $key ); if ( $position == - 1) echo ( "Element not found" ); else echo ( "Element Found at Position: " . ( $position + 1)); // This code is contributed by Ajit. ?> |
Javascript
<script> // Javascript program to implement linear // search in unsorted array // Function to implement search operation function findElement( arr, n, key) { let i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Driver program let arr = [12, 34, 10, 6, 40]; let n = arr.length; // Using a last element as search element let key = 40; let position = findElement(arr, n, key); if (position == - 1) document.write( "Element not found" ); else document.write( "Element Found at Position: " + (position + 1)); </script> |
Element Found at Position: 5
Time Complexity: O(n)
Auxiliary Space: O(1)
Insert at the end
In an unsorted array, the insert operation is faster as compared to a sorted array because we don’t have to care about the position at which the element is to be placed.
C++
// C++ program to implement insert // operation in an unsorted array. #include <iostream> using namespace std; // Inserts a key in arr[] of given capacity. // n is current size of arr[]. This // function returns n + 1 if insertion // is successful, else n. int insertSorted( int arr[], int n, int key, int capacity) { // Cannot insert more elements if n is // already more than or equal to capacity if (n >= capacity) return n; arr[n] = key; return (n + 1); } // Driver Code int main() { int arr[20] = {12, 16, 20, 40, 50, 70}; int capacity = sizeof (arr) / sizeof (arr[0]); int n = 6; int i, key = 26; cout << "\n Before Insertion: " ; for (i = 0; i < n; i++) cout << arr[i]<< " " ; // Inserting key n = insertSorted(arr, n, key, capacity); cout << "\n After Insertion: " ; for (i = 0; i < n; i++) cout << arr[i] << " " ; return 0; } // This code is contributed by SHUBHAMSINGH10 |
C
// C program to implement insert // operation in an unsorted array. #include<stdio.h> // Inserts a key in arr[] of given capacity. // n is current size of arr[]. This // function returns n + 1 if insertion // is successful, else n. int insertSorted( int arr[], int n, int key, int capacity) { // Cannot insert more elements if n is // already more than or equal to capacity if (n >= capacity) return n; arr[n] = key; return (n + 1); } // Driver Code int main() { int arr[20] = {12, 16, 20, 40, 50, 70}; int capacity = sizeof (arr) / sizeof (arr[0]); int n = 6; int i, key = 26; printf ( "\n Before Insertion: " ); for (i = 0; i < n; i++) printf ( "%d " , arr[i]); // Inserting key n = insertSorted(arr, n, key, capacity); printf ( "\n After Insertion: " ); for (i = 0; i < n; i++) printf ( "%d " ,arr[i]); return 0; } |
Java
// Java program to implement insert // operation in an unsorted array. class Main { // Function to insert a given key in // the array. This function returns n+1 // if insertion is successful, else n. static int insertSorted( int arr[], int n, int key, int capacity) { // Cannot insert more elements if n // is already more than or equal to // capacity if (n >= capacity) return n; arr[n] = key; return (n + 1 ); } // Driver Code public static void main (String[] args) { int [] arr = new int [ 20 ]; arr[ 0 ] = 12 ; arr[ 1 ] = 16 ; arr[ 2 ] = 20 ; arr[ 3 ] = 40 ; arr[ 4 ] = 50 ; arr[ 5 ] = 70 ; int capacity = 20 ; int n = 6 ; int i, key = 26 ; System.out.print( "Before Insertion: " ); for (i = 0 ; i < n; i++) System.out.print(arr[i]+ " " ); // Inserting key n = insertSorted(arr, n, key, capacity); System.out.print( "\n After Insertion: " ); for (i = 0 ; i < n; i++) System.out.print(arr[i]+ " " ); } } |
Python3
# Python program for inserting # an element in an unsorted array # method to insert element def insert(arr, element): arr.append(element) # declaring array and key to insert arr = [ 12 , 16 , 20 , 40 , 50 , 70 ] key = 26 # array before inserting an element print ( "Before Inserting: " ) print (arr) # array after Inserting element insert(arr, key) print ( "After Inserting: " ) print (arr) # Thanks to Aditi Sharma for contributing # this code |
C#
// C# program to implement insert // operation in an unsorted array. using System; class main { // Function to insert a given // key in the array. This // function returns n + 1 // if insertion is successful, // else n. static int insertSorted( int []arr, int n, int key, int capacity) { // Cannot insert more elements // if n is already more than // or equal to capacity if (n >= capacity) return n; arr[n] = key; return (n + 1); } // Driver Code public static void Main () { int [] arr = new int [20]; arr[0] = 12; arr[1] = 16; arr[2] = 20; arr[3] = 40; arr[4] = 50; arr[5] = 70; int capacity = 20; int n = 6; int i, key = 26; Console.Write( "Before Insertion: " ); for (i = 0; i < n; i++) Console.Write(arr[i]+ " " ); Console.WriteLine(); // Inserting key n = insertSorted(arr, n, key, capacity); Console.Write( "After Insertion: " ); for (i = 0; i < n; i++) Console.Write(arr[i]+ " " ); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to implement insert // operation in an unsorted array. // Inserts a key in arr[] of given // capacity. n is current size of arr[]. // This function returns n + 1 if // insertion is successful, else n. function insertSorted(& $arr , $n , $key , $capacity ) { // Cannot insert more elements if n is // already more than or equal to capacity if ( $n >= $capacity ) return $n ; array_push ( $arr , $key ); return ( $n + 1); } // Driver Code $arr = array (12, 16, 20, 40, 50, 70); $capacity = 20; $n = 6; $key = 26; echo "Before Insertion: " ; for ( $i = 0; $i < $n ; $i ++) echo $arr [ $i ] . " " ; // Inserting key $n = insertSorted( $arr , $n , $key , $capacity ); echo "\nAfter Insertion: " ; for ( $i = 0; $i < $n ; $i ++) echo $arr [ $i ] . " " ; // This code is contributed by // Rajput-Ji ?> |
Javascript
<script> // Javascript program to implement insert // operation in an unsorted array. // Function to insert a given // key in the array. This // function returns n + 1 // if insertion is successful, // else n. function insertSorted(arr, n, key, capacity) { // Cannot insert more elements // if n is already more than // or equal to capacity if (n >= capacity) return n; arr[n] = key; return (n + 1); } let arr = new Array(20); arr[0] = 12; arr[1] = 16; arr[2] = 20; arr[3] = 40; arr[4] = 50; arr[5] = 70; let capacity = 20; let n = 6; let i, key = 26; document.write( "Before Insertion: " ); for (i = 0; i < n; i++) document.write(arr[i]+ " " ); document.write( "</br>" ); // Inserting key n = insertSorted(arr, n, key, capacity); document.write( "After Insertion: " ); for (i = 0; i < n; i++) document.write(arr[i]+ " " ); </script> |
Before Insertion: 12 16 20 40 50 70 After Insertion: 12 16 20 40 50 70 26
Time Complexity: O(1)
Auxiliary Space: O(1)
Delete Operation
In the delete operation, the element to be deleted is searched using the linear search, and then delete operation is performed followed by shifting the elements.
C++
// C++ program to implement delete operation in a // unsorted array #include <iostream> using namespace std; // To search a key to be deleted int findElement( int arr[], int n, int key); // Function to delete an element int deleteElement( int arr[], int n, int key) { // Find position of element to be deleted int pos = findElement(arr, n, key); if (pos == - 1) { cout << "Element not found" ; return n; } // Deleting element int i; for (i = pos; i < n - 1; i++) arr[i] = arr[i + 1]; return n - 1; } // Function to implement search operation int findElement( int arr[], int n, int key) { int i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return - 1; } // Driver code int main() { int i; int arr[] = {10, 50, 30, 40, 20}; int n = sizeof (arr) / sizeof (arr[0]); int key = 30; cout << "Array before deletion\n" ; for (i = 0; i < n; i++) cout << arr[i] << " " ; n = deleteElement(arr, n, key); cout << "\n\nArray after deletion\n" ; for (i = 0; i < n; i++) cout << arr[i] << " " ; return 0; } // This code is contributed by shubhamsingh10 |
C
// C program to implement delete operation in a // unsorted array #include<stdio.h> // To search a key to be deleted int findElement( int arr[], int n, int key); // Function to delete an element int deleteElement( int arr[], int n, int key) { // Find position of element to be deleted int pos = findElement(arr, n, key); if (pos == - 1) { printf ( "Element not found" ); return n; } // Deleting element int i; for (i = pos; i < n - 1; i++) arr[i] = arr[i + 1]; return n - 1; } // Function to implement search operation int findElement( int arr[], int n, int key) { int i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return - 1; } // Driver code int main() { int i; int arr[] = {10, 50, 30, 40, 20}; int n = sizeof (arr) / sizeof (arr[0]); int key = 30; printf ( "Array before deletion\n" ); for (i = 0; i < n; i++) printf ( "%d " , arr[i]); n = deleteElement(arr, n, key); printf ( "\nArray after deletion\n" ); for (i = 0; i < n; i++) printf ( "%d " , arr[i]); return 0; } |
Java
// Java program to implement delete // operation in an unsorted array class Main { // function to search a key to // be deleted static int findElement( int arr[], int n, int key) { int i; for (i = 0 ; i < n; i++) if (arr[i] == key) return i; return - 1 ; } // Function to delete an element static int deleteElement( int arr[], int n, int key) { // Find position of element to be // deleted int pos = findElement(arr, n, key); if (pos == - 1 ) { System.out.println( "Element not found" ); return n; } // Deleting element int i; for (i = pos; i< n - 1 ; i++) arr[i] = arr[i + 1 ]; return n - 1 ; } // Driver Code public static void main(String args[]) { int i; int arr[] = { 10 , 50 , 30 , 40 , 20 }; int n = arr.length; int key = 30 ; System.out.println( "Array before deletion" ); for (i= 0 ; i<n; i++) System.out.print(arr[i] + " " ); n = deleteElement(arr, n, key); System.out.println( "\n\nArray after deletion" ); for (i= 0 ; i<n; i++) System.out.print(arr[i]+ " " ); } } |
Python3
# Python program to delete an element # from an unsorted array # Declaring array and key to delete arr = [ 10 , 50 , 30 , 40 , 20 ] key = 30 print ( "Array before deletion:" ) print (arr) # deletes key if found in the array # otherwise shows error not in list arr.remove(key) print ( "Array after deletion" ) print (arr) # This code is contributed by Aditi Sharma. |
C#
// C# program to implement delete // operation in an unsorted array using System; class main { // Function to search a // key to be deleted static int findElement( int []arr, int n, int key) { int i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Function to delete an element static int deleteElement( int []arr, int n, int key) { // Find position of element // to be deleted int pos = findElement(arr, n, key); if (pos == - 1) { Console.WriteLine( "Element not found" ); return n; } // Deleting element int i; for (i = pos; i < n - 1; i++) arr[i] = arr[i + 1]; return n - 1; } // Driver Code public static void Main() { int i; int []arr = {10, 50, 30, 40, 20}; int n = arr.Length; int key = 30; Console.Write( "Array before deletion " ); for (i = 0; i < n; i++) Console.Write(arr[i] + " " ); Console.WriteLine(); n = deleteElement(arr, n, key); Console.Write( "Array after deletion " ); for (i = 0; i < n; i++) Console.Write(arr[i]+ " " ); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to implement delete // operation in an unsorted array // To search a key to be deleted function findElement(& $arr , $n , $key ) { for ( $i = 0; $i < $n ; $i ++) if ( $arr [ $i ] == $key ) return $i ; return -1; } // Function to delete an element function deleteElement(& $arr , $n , $key ) { // Find position of element to // be deleted $pos = findElement( $arr , $n , $key ); if ( $pos == -1) { echo "Element not found" ; return $n ; } // Deleting element for ( $i = $pos ; $i < $n - 1; $i ++) $arr [ $i ] = $arr [ $i + 1]; return $n - 1; } // Driver code $arr = array (10, 50, 30, 40, 20); $n = count ( $arr ); $key = 30; echo "Array before deletion\n" ; for ( $i = 0; $i < $n ; $i ++) echo $arr [ $i ] . " " ; $n = deleteElement( $arr , $n , $key ); echo "\nArray after deletion\n" ; for ( $i = 0; $i < $n ; $i ++) echo $arr [ $i ] . " " ; // This code is contributed by // Rajput-Ji ?> |
Javascript
<script> // Java script program to implement delete // operation in an unsorted array // function to search a key to // be deleted function findElement(arr,n,key) { let i; for (i = 0; i < n; i++) if (arr[i] == key) return i; return -1; } // Function to delete an element function deleteElement(arr,n,key) { // Find position of element to be // deleted let pos = findElement(arr, n, key); if (pos == -1) { document.write( "Element not found" ); return n; } // Deleting element let i; for (i = pos; i< n - 1; i++) arr[i] = arr[i + 1]; return n - 1; } // Driver Code let i; let arr = [10, 50, 30, 40, 20]; let n = arr.length; let key = 30; document.write( "Array before deletion<br>" ); for (i=0; i<n; i++) document.write(arr[i] + " " ); n = deleteElement(arr, n, key); document.write( "<br><br>Array after deletion<br>" ); for (i=0; i<n; i++) document.write(arr[i]+ " " ); // This code is contributed by sravan kumar Gottumukkala </script> |
Array before deletion 10 50 30 40 20 Array after deletion 10 50 40 20
Time Complexity: O(n)
Auxiliary Space: O(1)
Time complexities:
Search: O(n)
Insert: O(1)
Delete: O(n)
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