dead, Java - rextester

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//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester
{  
    public static void main(String[] args){
    int n = 40; //Integer.parseInt(args[0]);
    int trials = 10; //Integer.parseInt(args[1]);
    int deadEnds = 0;

for (int t = 0; t < trials; t++){
      boolean[][] a = new boolean[n][n];
      int x = n/2;
      int y = n/2;

while ((x > 0) && (x < (n-1)) && (y > 0) && (y < (n-1))){
        a[x][y] = true;

if (a[x-1][y] && a[x+1][y] && a[x][y-1] && a[x][y+1]){
            deadEnds++;
            break;
        }

double r = Math.random();
        if (r < 0.25){
          if (!a[x+1][y]) x++;
        }
        else if (r < 0.50){
          if (!a[x-1][y]) x--;
        }
        else if (r < 0.75){
          if (!a[x][y+1]) y++;
        }
        else if (r < 1.00){
          if (!a[x][y-1]) y--;
        }

}
    }
    //System.out.println(deadEnds);
    System.out.println(100*deadEnds/trials + "% dead ends");
  }
}

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Compilation time: 0.63 sec, absolute running time: 0.14 sec, cpu time: 0.12 sec, memory peak: 18 Mb, absolute service time: 0,78 sec