题目来自《Thinking in Java》第四版，第四章最后一道练习题。 下面是我的代码：
public static void main(String args[]) { long t1 = System.currentTimeMillis(); int number = 0; int[] combo = new int[4]; left: for(int left=11;left<100;left++) { right: for(int right=11;right<=left;right++) { number = left * right; if(number < 1000 || (number-left-right) % 9 != 0 || number % 100 == 0) { continue right; } combo[0] = left / 10; combo[1] = left % 10; combo[2] = right / 10; combo[3] = right % 10; A: for(int a=0;a<=3;a++) { B: for(int b=0;b<=3;b++) { if(a == b) { continue; } C: for(int c=0;c<=3;c++) { if(c == a || c == b) { continue; } D: for(int d=0;d<=3;d++) { if(d == a || d == b || d == c) { continue; } int n = combo[a] * 1000 + combo[b] * 100 + combo[c] * 10 + combo[d]; if(n == number) { out(n + "=" + left + "*" + right);//这里自己替换成System.out.println() continue right; } continue C; } } } } } } long t2 = System.currentTimeMillis(); out("耗时：" + (t2-t1));//这里自己替换成System.out.println() }控制台输出结果：
