Implementation of Java full permutation algorithm---small example

Question: the equation of Guess

Look at the following equation:

--x--=--x---

It means: two double-digit multiplication equals a two-digit number multiplied by a three-digit number.

If there are no qualifying conditions, there are many examples.

However, the current limit is: The 9 blocks, representing the 1~9 9 numbers, does not contain 0.

Each number from 1 to 9 in the calculation appears and appears only once!

Like what:

x = x 158

x = 138 X

x = 186 X

.....

Please program, output all possible situations!

Attention:

The two multiplier on the left is the same scheme, do not repeat the output!

Output order of different scenarios is not important

Ideas:

See this question, immediately think of the use of brute force to solve the problem, that is: write a few layers for the loop to operate, but, too cumbersome, I think, there are no other ideas, Lenovo to the previous paragraph looked at the full permutation algorithm, and then, the use of this idea to encode, the source code is as follows:

/**
* @ Shishihu
*
*/
public class Question3 {
public static int total = 0; Record the number of formulas that match the criteria

Exchange two values
public static void Swap (int[] intarrs, int i, int j) {
int temp;
temp = Intarrs[i];
Intarrs[i] = Intarrs[j];
INTARRS[J] = temp;
}

Full permutation algorithm
public static void Arrange (int[] intarrs, int st, int len) {
if (st = = len-1) {
if (Intarrs[0] < intarrs[2]) {
if ((intarrs[0] * + intarrs[1]) * (intarrs[2] * + intarrs[3]) = = ((intarrs[4] * + intarrs[5]) * (intarrs[6] * 100 + intarrs[7] * + intarrs[8])) {
System.out.println (Intarrs[0] + "" + intarrs[1] + "*" + intarrs[2] + "+ intarrs[3" + "=" + intarrs[4] + "" + intarrs[5 ] + "*" + intarrs[6] + "" + intarrs[7] + "" + intarrs[8]);
total++;
}
}
Print all the full array
/*for (int i = 0; i < len; i++) {
System.out.print (Intarrs[i] + "");
}*/
} else {
for (int i = st; i < Len; i++) {
Swap (Intarrs, St, i);
Arrange (Intarrs, St + 1, Len);
Swap (Intarrs, St, i);
}
}
}
public static void Main (string[] args) {
int intarrs[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
Arrange (intarrs, 0, intarrs.length);
SYSTEM.OUT.PRINTLN (total);
}
}

Printing results:

46 * 79 = 23 * 158
54 * 69 = 27 * 138
54 * 93 = 27 * 186
58 * 67 = 29 * 134
58 * 69 = 23 * 174
58 * 73 = 29 * 146
58 * 96 = 32 * 174
63 * 74 = 18 * 259
64 * 79 = 32 * 158
73 * 96 = 12 * 584
76 * 98 = 14 * 532
11

Implementation of Java full permutation algorithm---small example