4个10以内的数字，通过四则运算得到24
请你用java写一个方法，判断给定的4个数字，每个数值在1~10之间，通过+ - * / 运算，结果为24，每个数字必须使用且只能使用一次。网友提供的穷举法
<div class="highlighter">
[*]public class T {
[*] int[] can = new int;
[*]<span />
[*] public static void main(String[] args) {
[*] T tf = new T(3, 4, 5, 7);
[*] System.out.println(tf.getResult());
[*] }
[*]<span />
[*] public T(int a, int b, int c, int d) {
[*] can = a;
[*] can = b;
[*] can = c;
[*] can = d;
[*] }
[*]<span />
[*] public String getResult() {
[*] double result1 = 0;
[*] double result2 = 0;
[*] double result3 = 0;
[*] for (int i = 0; i < 4; i++) {
[*] for (int j = 0; j < 4; j++) {
[*] for (int k = 0; k < 4; k++) {
[*] if (i != j) {
[*] result1 = cal(can, can, k);
[*] for (int l = 0; l < 4; l++) {
[*] for (int m = 0; m < 4; m++) {
[*] if (i != l && j != l) {
[*] result2 = cal(result1, can, m);
[*] for (int n = 0; n < 4; n++) {
[*] for (int o = 0; o < 4; o++) {
[*] if (i != n && j != n && l != n) {
[*] result3 = cal(result2, can, o);
[*] if (result3 == 24) {
[*] return result(can, k, can, m, can, o, can);
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] }
[*] return null;
[*] }
[*]<span />
[*] private String result(int can1, int op1, int can2, int op2, int can3, int op3, int can4) {
[*] return "" + can1 + convert(op1) + can2 + convert(op2) + can3 + convert(op3) + can4;
[*] }
[*]<span />
[*] private String convert(int opr) {
[*] if (opr == 0) {
[*] return "+";
[*] } else if (opr == 1) {
[*] return "-";
[*] } else if (opr == 2) {
[*] return "*";
[*] } else if (opr == 3) {
[*] return "/";
[*] }
[*] return "";
[*] }
[*]<span />
[*] private double cal(double a, double b, int opr) {
[*] if (opr == 0) {
[*] return a + b;
[*] } else if (opr == 1) {
[*] return a - b;
[*] } else if (opr == 2) {
[*] return a * b;
[*] } else if (opr == 3) {
[*] return a / b;
[*] }
[*] return 0;
[*] }
[*]}
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