Wednesday, June 14, 2017

Nth Digit


Problem Statement

Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...
Note:
n is positive and will fit within the range of a 32-bit signed integer (n < 231).

Link to gitHub :Code


Example
Example 1

Input:    Output:
3         3

Example 2
Input:    Output:
11         0

Explanation:
The 11th digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... is a 0, 
which is part of the number 10.

Solution

  • Find the length of the number where the nth digit is from
  • Find the actual number where the nth digit is from
  • Find the nth digit and return
public static int Get(int n)
 {
  int len=1;
  long count =9;
  int start=1;
  
  while(n>len*count)
  {
   n-=len*count;
   len+=1;
   count*=10;
   start*=10;
   
  }
  start+=(n-1)/len;
  
  //Convert to string
  String s=Integer.toString(start);
  //return the numeric value
  return Character.getNumericValue(s.charAt((n-1)% len));
  
  
 }

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