Chef and his cake.java

/* package codechef; // don't place package name! */

import java.util.Scanner;
import java.util.Stack;

/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
    public static void main (String[] args) throws java.lang.Exception
    {
        Scanner sc = new Scanner(System.in);
        int T = sc.nextInt();
        
        for (int i = 0; i < T; i++)
        {
            int N = sc.nextInt();
            int M = sc.nextInt();
            int downcost = 0;
            int upcost = 0;
            Stack<Character> stack = new Stack<>();
           
            String strLine = "";
            for (int j = 0; j < N; j++)
            {
                strLine = strLine + sc.next();
            }
            char line[] = strLine.toCharArray();
            
            char top = line[0];
            stack.push(top);
            for (int j = 1; j < line.length ; j++)
            {
                if(line[j]==top)
                {
                    if(line[j]=='R')
                    {
                        upcost = upcost + 5;
                        top = 'G';
                    }
                    else
                    {
                        upcost = upcost + 3;
                        top = 'R';
                    }
                    stack.push(line[j]);
                    continue;
                }
    
                top = line[j];
                stack.push(line[j]);
            }
            
            
            
            
            char prev = stack.pop();
            while (!stack.isEmpty())
            {
                char cur = stack.pop();
                if(cur==prev)
                {
                    if(cur=='R')
                    {
                        downcost = downcost + 5;
                        prev = 'G';
                    }
                    else
                    {
                        downcost = downcost + 3;
                        prev = 'R';
                    }
                    continue;
                }
                
                prev = cur;
            }
            
            System.out.println((downcost<upcost)?downcost:upcost);
        }
    }
}