Insert Element at a Given Position in an Array
Last Updated :
07 Nov, 2024
Given an array of integers, the task is to insert an element at a given position in the array.
Examples:
Input: arr[] = [10, 20, 30, 40], pos = 2, ele = 50
Output: [10, 50, 20, 30, 40]
Input: arr[] = [], pos = 1, ele = 20
Output: [20]
Input: arr[] = [10, 20, 30, 40], pos = 5, ele = 50
Output: [10, 20, 30, 40, 50]
[Approach 1] Using Built-In Methods
We will use library methods like insert() in C++, Python and C#, add() in Java and splice() in JavaScript.
C++
// C++ program to insert given element at a given position
// in an array using in-built methods
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector<int> arr = {10, 20, 30, 40};
int ele = 50;
int pos = 2;
cout << "Array before insertion\n";
for (int i = 0; i < arr.size(); i++)
cout << arr[i] << " ";
// Insert element at the given position
arr.insert(arr.begin() + pos - 1, ele);
cout << "\nArray after insertion\n";
for (int i = 0; i < arr.size(); i++)
cout << arr[i] << " ";
return 0;
}
// Java program to insert given element at a given position
// in an array using in-built methods
import java.util.ArrayList;
import java.util.Arrays;
class GfG {
public static void main(String[] args) {
ArrayList<Integer> arr = new
ArrayList<>(Arrays.asList(10, 20, 30, 40));
int ele = 50;
int pos = 2;
System.out.println("Array before insertion");
for (int i = 0; i < arr.size(); i++)
System.out.print(arr.get(i) + " ");
// Insert element at the given position
arr.add(pos - 1, ele);
System.out.println("\nArray after insertion");
for (int i = 0; i < arr.size(); i++)
System.out.print(arr.get(i) + " ");
}
}
# Python program to insert given element at a given position
# in an array using in-built methods
if __name__ == "__main__":
arr = [10, 20, 30, 40]
ele = 50
pos = 2
print("Array before insertion")
print(arr)
# Insert element at the given position
arr.insert(pos - 1, ele)
print("Array after insertion")
print(arr)
// C# program to insert given element at a given position
// in an array using in-built methods
using System;
using System.Collections.Generic;
class GfG {
static void Main() {
List<int> arr = new List<int> { 10, 20, 30, 40 };
int ele = 50;
int pos = 2;
Console.WriteLine("Array before insertion");
foreach (var item in arr)
Console.Write(item + " ");
// Insert element at the given position
arr.Insert(pos - 1, ele);
Console.WriteLine("\nArray after insertion");
foreach (var item in arr)
Console.Write(item + " ");
}
}
// JavaScript program to insert given element at a given position
// in an array using in-built methods
let arr = [10, 20, 30, 40];
let ele = 50;
let pos = 2;
console.log("Array before insertion");
console.log(arr);
// Insert element at the given position
arr.splice(pos - 1, 0, ele);
console.log("Array after insertion");
console.log(arr);
OutputArray before insertion
10 20 30 40
Array after insertion
10 50 20 30 40
Time Complexity: O(n), where n is the size of the array.
[Approach 2] Using Custom Method
To add an element at a given position in an array, shift all the elements from that position one index to the right, and after shifting insert the new element at the required position.
C++
// C++ program to insert given element at a given position
// in an array using custom method
#include <iostream>
#include <vector>
using namespace std;
int main() {
int n = 4;
vector<int> arr = {10, 20, 30, 40, 0};
int ele = 50;
int pos = 2;
cout << "Array before insertion\n";
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
// Shifting elements to the right
for(int i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// Insert the new element at index pos - 1
arr[pos - 1] = ele;
cout << "\nArray after insertion\n";
for (int i = 0; i <= n; i++)
cout << arr[i] << " ";
return 0;
}
// C program to insert given element at a given position
// in an array using custom method
#include <stdio.h>
#include <string.h>
int main() {
int n = 4;
int arr[] = {10, 20, 30, 40, 0};
int ele = 50;
int pos = 2;
printf("Array before insertion\n");
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
// Shifting elements to the right
for(int i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// Insert the new element at index pos - 1
arr[pos - 1] = ele;
printf("\nArray after insertion\n");
for (int i = 0; i <= n; i++)
printf("%d ", arr[i]);
return 0;
}
// Java program to insert given element at a given position
// in an array using custom method
import java.util.Arrays;
class GfG {
public static void main(String[] args) {
int n = 4;
int[] arr = {10, 20, 30, 40, 0};
int ele = 50;
int pos = 2;
System.out.println("Array before insertion");
for (int i = 0; i < n; i++)
System.out.print(arr[i] + " ");
// Shifting elements to the right
for (int i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// Insert the new element at index pos - 1
arr[pos - 1] = ele;
System.out.println("\nArray after insertion");
for (int i = 0; i <= n; i++)
System.out.print(arr[i] + " ");
}
}
# Python program to insert given element at a given position
# in an array using custom method
if __name__ == "__main__":
n = 4
arr = [10, 20, 30, 40, 0]
ele = 50
pos = 2
print("Array before insertion")
for i in range(n):
print(arr[i], end=' ')
# Shifting elements to the right
for i in range(n, pos - 1, -1):
arr[i] = arr[i - 1]
# Insert the new element at index pos - 1
arr[pos - 1] = ele
print("\nArray after insertion")
for i in range(n + 1):
print(arr[i], end=' ')
// C# program to insert given element at a given position
// in an array using custom method
using System;
class GfG {
static void Main() {
int n = 4;
int[] arr = {10, 20, 30, 40, 0};
int ele = 50;
int pos = 2;
Console.WriteLine("Array before insertion");
for (int i = 0; i < n; i++)
Console.Write(arr[i] + " ");
// Shifting elements to the right
for (int i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// Insert the new element at index pos - 1
arr[pos - 1] = ele;
Console.WriteLine("\nArray after insertion");
for (int i = 0; i <= n; i++)
Console.Write(arr[i] + " ");
}
}
// JavaScript program to insert given element at a given
// position in an array using custom method
let n = 4;
let arr = [10, 20, 30, 40, 0];
let ele = 50;
let pos = 2;
console.log("Array before insertion");
console.log(arr);
// Shifting elements to the right
for (let i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// Insert the new element at index pos - 1
arr[pos - 1] = ele;
console.log("\nArray after insertion");
console.log(arr);
OutputArray before insertion
10 20 30 40
Array after insertion
10 50 20 30 40
Time Complexity: O(n), where n is the size of the array.
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