Number format exception Java doubt

#1

Hi,
Number format exception is coming .Please check.

#2

reply…

#3

if we try to parse a string to integer but the string is null,The NumberFormatException is thrown.

  • Example- Integer.parseInt("");
    handle that case
#4

https://ide.codingblocks.com/s/471255 TLE is coming now. Please check

#5

use this approach for O(kn)

  1. Make a function remove Kdigits and pass String N and int k as parameter
    remove     Kdigits(String N,int K)

  2. Create StringBuilder sb, inside the Function
    due to In java, string objects are immutable. Immutable simply means unmodifiable or unchangeable. (We want to delete K char from the String)

  3. Create Stack of character S

  4. loop from value i=0 to till i<N.length()
    Inside the loop
    `while (k > 0 && !s.isEmpty() && s.peek() > n.charAt(i)) {
    s.pop();
    k–;
    }
    s.push(ch);
    }
    Aim to make the smallest number
    If s.peek() > n.charAt(i) then remove bigger number
    We remove only K Character
    If stack is Empty you can’t remove anything

  5. After completion of 4th step
    Stack based on the basic principle of last-in-first-out,
    pop Character from Stack s and add First Index of Sb.until and unless Stack is Empty

  6. Above loop will not remove K Character in some cases. Then follow these steps

Example N=”1324567” K =3
Then sb = “124567”
if the length of sb > length of String N - K, means Character digits are in Increasing order then remove the K Character from last.
Sb = sb.subString(0,N-k+1)// remove total K character
if sb.charAt(0)==’0’
Sb = sb.subString(1)//remove leading 0’s
If sb.length()==0
Return “0” from function //0 is positive smallest number
Else
Return sb;

Solution Link : https://ide.codingblocks.com/s/191861