Strange Grid

A strange grid has been recovered from an old book. It has 5 columns and infinite number of rows. The bottom row is considered as the first row. First few rows of the grid are like this:

..............

..............

20 22 24 26 28

11 13 15 17 19

10 12 14 16 18

 1  3  5  7  9

 0  2  4  6  8

The grid grows upwards forever!

Your task is to find the integer in cth column in rth row of the grid.

Input Format

There will be two integers r and c separated by a single space.

Constraints

1≤r≤2 * 109

1≤c≤5

Rows are indexed from bottom to top and columns are indexed from left to right.

Output Format

Output the answer in a single line.

Sample Input

6 3

Sample Output

25

Explanation

The number in the 6th row and 3rd column is 25.

 

Java:

import java.util.Scanner;

public class Solution {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
long r = input.nextLong(); //row index
long c = input.nextLong(); //column index
//rows and columns start from 0
–r;
–c;
//as we can see
//even row: start with r*10
//odd row: start with r*10+1
//so the problem is really that easy
System.out.println( (r%2 == 0) ? (r/2*10+c*2) : ( (r/2*10+1) + c*2));

}
}

Advertisements