Program to delete Nth digit of a Number
Last Updated :
30 Jun, 2022
Given a number num and a number n, the task is to delete this nth digit of the number num, from starting and from end.
Examples:
Input: num = 1234, n = 3
Output: num_after_deleting_from_starting = 124, num_after_deleting_from_end = 134
Input: num = 4516312, n = 2
Output: num_after_deleting_from_starting = 416312, num_after_deleting_from_end = 451632
Approach:
- To delete nth digit from starting:
- Get the number and the nth digit to be deleted.
- Count the number of digits
- Loop number of digits time by counting it with a variable i.
- If the i is equal to (number of digits - n), then skip, else add the ith digit as [ new_number = (new_number * 10) + ith_digit ].
- To delete nth digit from ending:
- Get the number and the nth digit to be deleted.
- Loop number of digits time by counting it with a variable i.
- If the i is equal to (n), then skip, else add the ith digit as [ new_number = (new_number * 10) + ith_digit ].
Implementation:
C++
// C++ implementation of above approach
#include <bits/stdc++.h>
using namespace std;
// Function to delete nth digit
// from starting
int deleteFromStart(int num, int n)
{
// Get the number of digits
int d = log10(num) + 1;
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 0; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == (d - n)) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Function to delete nth digit
// from ending
int deleteFromEnd(int num, int n)
{
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 1; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == n) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Driver code
int main()
{
// Get the number
int num = 1234;
cout << "Number: " << num << endl;
// Get the digit number to be deleted
int n = 3;
cout << "Digit to be deleted: " << n << endl;
// Remove the nth digit from starting
cout << "Number after " << n
<< " digit deleted from starting: "
<< deleteFromStart(num, n) << endl;
// Remove the nth digit from ending
cout << "Number after " << n
<< " digit deleted from ending: "
<< deleteFromEnd(num, n) << endl;
return 0;
}
// Java implementation of above approach
class GFG
{
// Function to delete nth digit
// from starting
static int deleteFromStart(int num, int n)
{
// Get the number of digits
int d = (int)Math.log10(num) + 1;
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 0; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == (d - n)) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Function to delete nth digit
// from ending
static int deleteFromEnd(int num, int n)
{
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 1; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == n) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Driver code
public static void main(String []args)
{
// Get the number
int num = 1234;
System.out.println("Number: " + num );
// Get the digit number to be deleted
int n = 3;
System.out.println("Digit to be deleted: " + n );
// Remove the nth digit from starting
System.out.println("Number after " + n
+ " digit deleted from starting: "
+ deleteFromStart(num, n));
// Remove the nth digit from ending
System.out.println( "Number after " + n
+ " digit deleted from ending: "
+ deleteFromEnd(num, n));
}
}
// This code is contributed by ihritik
# Python3 implementation of above approach
# Function to delete nth digit
# from starting
import math;
def deleteFromStart(num, n):
# Get the number of digits
d = (math.log10(num) + 1);
# Declare a variable to form
# the reverse resultant number
rev_new_num = 0;
# Loop with the number
i = 0;
while (num != 0):
digit = num % 10;
num = int(num / 10);
if (i != (int(d) - n)):
rev_new_num = ((rev_new_num * 10) +
digit);
i += 1;
# Declare a variable to form the
# resultant number
new_num = 0;
# Loop with the number
i = 0;
while (rev_new_num != 0):
new_num = ((new_num * 10) +
(rev_new_num % 10));
rev_new_num = int(rev_new_num / 10);
i += 1;
# Return the resultant number
return new_num;
# Function to delete nth digit
# from ending
def deleteFromEnd(num, n):
# Declare a variable to form
# the reverse resultant number
rev_new_num = 0;
# Loop with the number
i = 1;
while (num != 0):
digit = num % 10;
num = int(num / 10);
if (i != n):
rev_new_num = ((rev_new_num * 10) +
digit);
i += 1;
# Declare a variable
# to form the resultant number
new_num = 0;
# Loop with the number
i = 0;
while (rev_new_num != 0):
new_num = ((new_num * 10) +
(rev_new_num % 10));
rev_new_num = int(rev_new_num / 10);
i += 1;
# Return the resultant number
return new_num;
# Driver code
# Get the number
num = 1234;
print("Number:", num);
# Get the digit number to be deleted
n = 3;
print("Digit to be deleted:", n);
# Remove the nth digit from starting
print("Number after", n,
"digit deleted from starting:",
deleteFromStart(num, n));
# Remove the nth digit from ending
print("Number after", n,
"digit deleted from ending:",
deleteFromEnd(num, n));
# This code is contributed by chandan_jnu
// C# implementation of the above approach
using System;
class GFG
{
// Function to delete nth digit
// from starting
static int deleteFromStart(int num, int n)
{
// Get the number of digits
int d = (int)Math.Log10(num) + 1;
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 0; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == (d - n)) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Function to delete nth digit
// from ending
static int deleteFromEnd(int num, int n)
{
// Declare a variable
// to form the reverse resultant number
int rev_new_num = 0;
// Loop with the number
for (int i = 1; num != 0; i++) {
int digit = num % 10;
num = num / 10;
if (i == n) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
int new_num = 0;
// Loop with the number
for (int i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = rev_new_num / 10;
}
// Return the resultant number
return new_num;
}
// Driver code
public static void Main()
{
// Get the number
int num = 1234;
Console.WriteLine("Number: " + num );
// Get the digit number to be deleted
int n = 3;
Console.WriteLine("Digit to be deleted: " + n );
// Remove the nth digit from starting
Console.WriteLine("Number after " + n
+ " digit deleted from starting: "
+ deleteFromStart(num, n));
// Remove the nth digit from ending
Console.WriteLine( "Number after " + n
+ " digit deleted from ending: "
+ deleteFromEnd(num, n));
}
}
// This code is contributed by ihritik
<?php
//PHP implementation of above approach
// Function to delete nth digit
// from starting
function deleteFromStart($num, $n)
{
// Get the number of digits
$d = (log10($num) + 1);
// Declare a variable
// to form the reverse resultant number
$rev_new_num = 0;
// Loop with the number
for ($i = 0; $num != 0; $i++) {
$digit = $num % 10;
$num = (int)$num / 10;
if ($i == ($d - $n)) {
continue;
}
else {
$rev_new_num = ($rev_new_num * 10) + $digit;
}
}
// Declare a variable
// to form the resultant number
$new_num = 0;
// Loop with the number
for ($i = 0; $rev_new_num != 0; $i++) {
$new_num = ($new_num * 10)
+ ($rev_new_num % 10);
$rev_new_num = (int)$rev_new_num / 10;
}
// Return the resultant number
return $new_num;
}
// Function to delete nth digit
// from ending
function deleteFromEnd($num, $n)
{
// Declare a variable
// to form the reverse resultant number
$rev_new_num = 0;
// Loop with the number
for ($i = 1; $num != 0; $i++) {
$digit = $num % 10;
$num = (int)$num / 10;
if ($i == $n) {
continue;
}
else {
$rev_new_num = ($rev_new_num * 10) + $digit;
}
}
// Declare a variable
// to form the resultant number
$new_num = 0;
// Loop with the number
for ($i = 0; $rev_new_num != 0; $i++) {
$new_num = ($new_num * 10)
+ ($rev_new_num % 10);
$rev_new_num = (int)$rev_new_num / 10;
}
// Return the resultant number
return $new_num;
}
// Driver code
// Get the number
$num = 1234;
echo "Number: " , $num ,"\n";
// Get the digit number to be deleted
$n = 3;
echo "Digit to be deleted: " ,$n ,"\n";
// Remove the nth digit from starting
echo "Number after " , $n,
" digit deleted from starting: ",
deleteFromStart($num, $n),"\n";
// Remove the nth digit from ending
echo "Number after " , $n,
" digit deleted from ending: ",
deleteFromEnd($num, $n) ,"\n";
?>
// This code is contributed by jit_t.
<script>
// Javascript implementation of
// the above approach
// Function to delete nth digit
// from starting
function deleteFromStart(num, n)
{
// Get the number of digits
let d = parseInt(Math.log10(num), 10) + 1;
// Declare a variable
// to form the reverse resultant number
let rev_new_num = 0;
// Loop with the number
for (let i = 0; num != 0; i++) {
let digit = num % 10;
num = parseInt(num / 10, 10);
if (i == (d - n)) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
let new_num = 0;
// Loop with the number
for (let i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = parseInt(rev_new_num / 10, 10);
}
// Return the resultant number
return new_num;
}
// Function to delete nth digit
// from ending
function deleteFromEnd(num, n)
{
// Declare a variable
// to form the reverse resultant number
let rev_new_num = 0;
// Loop with the number
for (let i = 1; num != 0; i++) {
let digit = num % 10;
num = parseInt(num / 10, 10);
if (i == n) {
continue;
}
else {
rev_new_num = (rev_new_num * 10) + digit;
}
}
// Declare a variable
// to form the resultant number
let new_num = 0;
// Loop with the number
for (let i = 0; rev_new_num != 0; i++) {
new_num = (new_num * 10)
+ (rev_new_num % 10);
rev_new_num = parseInt(rev_new_num / 10, 10);
}
// Return the resultant number
return new_num;
}
// Get the number
let num = 1234;
document.write("Number: " + num + "</br>");
// Get the digit number to be deleted
let n = 3;
document.write("Digit to be deleted: " + n + "</br>");
// Remove the nth digit from starting
document.write("Number after " + n
+ " digit deleted from starting: "
+ deleteFromStart(num, n) + "</br>");
// Remove the nth digit from ending
document.write( "Number after " + n
+ " digit deleted from ending: "
+ deleteFromEnd(num, n));
</script>
Output: Number: 1234
Digit to be deleted: 3
Number after 3 digit deleted from starting: 124
Number after 3 digit deleted from ending: 134
Complexity Analysis:
Time complexity: O(log(N)).
Auxiliary Space: O(1), since no extra space has been taken.
Another Approach: (To convert number into string)
C++
// C++ implementation to delete nth digit
// from starting with O(logN) time complexity.
#include<bits/stdc++.h>
using namespace std;
// function to delete nth number from starting
static string fromStart(string inp, int del)
{
string inp1 = inp.substr(0, del - 1);
string inp2 = inp.substr(del, inp.length());
return inp1 + inp2;
}
// function to delete nth number from ending
static string fromEnd(string inp, int del)
{
string inp1 = inp.substr(0, inp.length() - del);
string inp2 = inp.substr(inp.length() - del + 1,
inp.length());
return inp1 + inp2;
}
// Driver Code
int main()
{
int in = 1234;
// type cast input number to string
stringstream ss;
ss << in;
string inp = ss.str();
int del = 3;
cout << "num_after_deleting_from_starting "
<< fromStart(inp, del) << endl;
cout << "num_after_deleting_from_ending "
<< fromEnd(inp, del) << endl;
return 0;
}
// This code is contributed by chandan_jnu
// Java implementation to delete nth digit
// from starting with O(logN) time complexity.
public class DeleteN {
public static void main(String args[]) {
int in = 1234;
// type cast input number to string
String inp = Integer.toString(in);
int del = 3;
System.out.println("num_after_deleting_from_starting " + fromStart(inp, del));
System.out.println("num_after_deleting_from_ending " + fromEnd(inp, del));
}
// function to delete nth number from starting
static String fromStart(String inp, int del) {
try {
String inp1 = inp.substring(0, del - 1);
String inp2 = inp.substring(del, inp.length());
return inp1 + inp2;
}
catch (Exception e) {
return "Check Input";
}
}
// function to delete nth number from ending
static String fromEnd(String inp, int del) {
try {
String inp1 = inp.substring(0, inp.length() - del);
String inp2 = inp.substring(inp.length() - del + 1, inp.length());
return inp1 + inp2;
}
catch (Exception e) {
return "Check Input";
}
}
}
# Python3 implementation to delete nth digit
# from starting with O(logN) time complexity.
# function to del1ete nth number
# from starting
def fromStart(inp, del11):
inp1 = inp[0:del1 - 1];
inp2 = inp[del1:len(inp)];
return inp1 + inp2;
# function to delete nth number
# from ending
def fromEnd(inp, del1):
inp1 = inp[0:len(inp) - del1];
inp2 = inp[len(inp) - del1 + 1:len(inp)];
return inp1 + inp2;
# Driver Code
in1 = 1234;
# type cast input number to string
inp = str(in1);
del1 = 3;
print("num_after_deleting_from_starting",
fromStart(inp, del1));
print("num_after_deleting_from_ending",
fromEnd(inp, del1));
# This code is contributed by chandan_jnu
// C# implementation to delete nth digit
// from starting with O(logN) time complexity.
using System ;
public class DeleteN {
public static void Main() {
int num = 1234;
// type cast input number to string
string inp = Convert.ToString(num) ;
int del = 3;
Console.WriteLine("num_after_deleting_from_starting "
+ fromStart(inp, del));
Console.WriteLine("num_after_deleting_from_ending "
+ fromEnd(inp, del));
}
// function to delete nth number from starting
static String fromStart(string inp, int del) {
try {
string inp1 = inp.Substring(0, del - 1);
string inp2 = inp.Substring(del, inp.Length - del);
return inp1 + inp2;
}
catch (Exception ) {
return "Check Input";
}
}
// function to delete nth number from ending
static String fromEnd(string inp, int del) {
try {
string inp1 = inp.Substring(0, inp.Length - del);
string inp2 = inp.Substring(inp.Length - del + 1, del - 1);
return inp1 + inp2;
}
catch (Exception e) {
Console.WriteLine(e) ;
return "Check Input";
}
}
}
// This code is contributed by Ryuga
<?php
// PHP implementation to delete nth digit
// from starting with O(logN) time complexity.
// function to delete nth number from starting
function fromStart($inp, $del)
{
$inp1 = substr($inp, 0, $del - 1);
$inp2 = substr($inp, $del, strlen($inp));
return $inp1.$inp2;
}
// function to delete nth number from ending
function fromEnd($inp, $del)
{
$inp1 = substr($inp, 0, strlen($inp) - $del);
$inp2 = substr($inp, strlen($inp) - $del + 1,
strlen($inp));
return $inp1.$inp2;
}
// Driver Code
$in = 1234;
// type cast input number to string
$inp = strval($in);
$del = 3;
print("num_after_deleting_from_starting " .
fromStart($inp, $del) . "\n");
print("num_after_deleting_from_ending " .
fromEnd($inp, $del));
// This code is contributed by chandan_jnu
?>
<script>
// Javascript implementation to delete nth digit
// from starting with O(logN) time complexity.
// function to delete nth number from starting
function fromStart(inp, del) {
let inp1 = inp.substring(0, del - 1);
let inp2 = inp.substring(del, inp.length);
return inp1 + inp2;
}
function fromEnd(inp, del) {
let inp1 = inp.substring(0, inp.length - del);
let inp2 = inp.substring(inp.length - del + 1, inp.length - del + 1 + inp.length);
return inp1 + inp2;
}
let In = 1234;
// type cast input number to string
let inp = In.toString();
let del = 3;
document.write("num_after_deleting_from_starting " + fromStart(inp, del) + "</br>");
document.write("num_after_deleting_from_ending " + fromEnd(inp, del) + "</br>");
// This code is contributed by mukesh07.
</script>
Output:
num_after_deleting_from_starting 124
num_after_deleting_from_ending 134
Time complexity :O(log(N)).
Auxiliary Space: O(log(N)).
Similar Reads
DSA Tutorial - Learn Data Structures and Algorithms
DSA (Data Structures and Algorithms) is the study of organizing data efficiently using data structures like arrays, stacks, and trees, paired with step-by-step procedures (or algorithms) to solve problems effectively. Data structures manage how data is stored and accessed, while algorithms focus on
7 min read
Quick Sort
QuickSort is a sorting algorithm based on the Divide and Conquer that picks an element as a pivot and partitions the given array around the picked pivot by placing the pivot in its correct position in the sorted array. It works on the principle of divide and conquer, breaking down the problem into s
12 min read
Merge Sort - Data Structure and Algorithms Tutorials
Merge sort is a popular sorting algorithm known for its efficiency and stability. It follows the divide-and-conquer approach. It works by recursively dividing the input array into two halves, recursively sorting the two halves and finally merging them back together to obtain the sorted array. Merge
14 min read
Breadth First Search or BFS for a Graph
Given a undirected graph represented by an adjacency list adj, where each adj[i] represents the list of vertices connected to vertex i. Perform a Breadth First Search (BFS) traversal starting from vertex 0, visiting vertices from left to right according to the adjacency list, and return a list conta
15+ min read
Bubble Sort Algorithm
Bubble Sort is the simplest sorting algorithm that works by repeatedly swapping the adjacent elements if they are in the wrong order. This algorithm is not suitable for large data sets as its average and worst-case time complexity are quite high.We sort the array using multiple passes. After the fir
8 min read
Binary Search Algorithm - Iterative and Recursive Implementation
Binary Search Algorithm is a searching algorithm used in a sorted array by repeatedly dividing the search interval in half. The idea of binary search is to use the information that the array is sorted and reduce the time complexity to O(log N). Binary Search AlgorithmConditions to apply Binary Searc
15 min read
Insertion Sort Algorithm
Insertion sort is a simple sorting algorithm that works by iteratively inserting each element of an unsorted list into its correct position in a sorted portion of the list. It is like sorting playing cards in your hands. You split the cards into two groups: the sorted cards and the unsorted cards. T
9 min read
Data Structures Tutorial
Data structures are the fundamental building blocks of computer programming. They define how data is organized, stored, and manipulated within a program. Understanding data structures is very important for developing efficient and effective algorithms. What is Data Structure?A data structure is a st
2 min read
Dijkstra's Algorithm to find Shortest Paths from a Source to all
Given a weighted undirected graph represented as an edge list and a source vertex src, find the shortest path distances from the source vertex to all other vertices in the graph. The graph contains V vertices, numbered from 0 to V - 1.Note: The given graph does not contain any negative edge. Example
12 min read
Selection Sort
Selection Sort is a comparison-based sorting algorithm. It sorts an array by repeatedly selecting the smallest (or largest) element from the unsorted portion and swapping it with the first unsorted element. This process continues until the entire array is sorted.First we find the smallest element an
8 min read