java – How to optimize my code?

Question:

I am new to Java (programming in Pascal) and I need to write a program to solve the following problem (something like a number puzzle):

AB + CC = DC
CE * FB = CEB
FF * GC = GHC
AB - CE = FF
CC + FB = GC 
DC + CEB = GHC

P.S. Each character is one digit (from 0 to 9). Each digit can only be used once.

So I wrote the following program:

public class javaapplication1 {

    public static void main(String[] args) {
        boolean bb=false;
        for (int h = 0; h < 10; h++) {
            for (int g = 0; g < 10; g++) {
                if (bb) {
                    break;
                }
                for (int f = 0; f < 10; f++) {
                    if (bb) {
                        break;
                    }
                    for (int e = 0; e < 10; e++) {
                        if (bb) {
                            break;
                        }
                        for (int d = 0; d < 10; d++) {
                            if (bb) {
                                break;
                            }
                            for (int c = 0; c < 10; c++) {
                                if (bb) {
                                    break;
                                }
                                for (int b = 0; b < 10; b++) {
                                    if (bb) {
                                        break;
                                    }
                                    for (int a = 0; a < 10; a++) {
                                        if (a*10 + b + c*10 + c == d*10 + c) {
                                            if ((c*10+e)*(f*10+b)==(c*100+e*10+b)) {
                                                if ((f*10+f)*(g*10+c)==g*100+h*10+c) {
                                                    if ((a*10+b)-(c*10+e) == f*10+f) {
                                                        if ((c*10+c)+(f*10+b) == g*10+c) {
                                                            if ((d*10+c)+(c*100+e*10+b) == g*100+h*10+c) {
                                                                if (a!=b && a!=c && a!=d && a!=e && a!=f && a!=g && a!=h) {
                                                                    if (b!=c && b!=d && b!=e && b!=f && b!=g && b!=h) {
                                                                        if (c!=d && c!=e && c!=f && c!=g && c!=h) {
                                                                            if (d!=e && d!=f && d!=g && d!=h) {
                                                                                if (e!=f && e!=g && e!=h) {
                                                                                    if (f!=g && f!=h) {
                                                                                        if (g!=h) {
                                                                                            bb = true;
                                                                                            System.out.println(a);
                                                                                            System.out.println(b);
                                                                                            System.out.println(c);
                                                                                            System.out.println(d);
                                                                                            System.out.println(e);
                                                                                            System.out.println(f);
                                                                                            System.out.println(g);
                                                                                            System.out.println(h);
                                                                                            break;
                                                                                        }
                                                                                    }
                                                                                }
                                                                            }
                                                                        }
                                                                    }
                                                                }
                                                            }
                                                        }
                                                    }
                                                }
                                            }

                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

It works and produces the correct results, however I'm sure it's spelled wrong as the solution itself is stupid – pure bribery. Please show me how to optimize this program. Z.Y. I wrote a large number of if-s to a greater extent for greater code clarity for myself personally.

Answer:

1. There is no need to make a complex break through a boolean variable. return is enough, it will break all loops.
2. The condition "Each digit can be used only once" must be checked not at the very last, but at the stage of enumeration. So you will only have 10!/2!=10*9*8*7*6*5*4*3 checks, not 10^8 .
   1. Define the set of all digits.
   2. In the outer loop iterate over this set.
   3. In the next loop, iterate over the set from the previous loop without the digit that was selected in the previous loop.
   4. In the next loop, iterate over the set from the previous loop without the digit that was selected in the previous loop … and so on.
3. Conditions can be isolated and stored as a list of methods (lambdas), and then checked in a loop.