Java打印出ABCD四个字母的四位不相同组合，例如：ABCD、ACBD、ACDB… 提示：按照概率学来说，4个字母在不出现重复字母的的排列组合总计4
3
2*1=24种。并利用char与int之间的关系，循环int值，转换为char输出
for (int i = 65; i <= 68; i++) {
for (int j = 65; j <= 68; j++) {
if (i == j) {
continue;
}
for (int k = 65; k <= 68; k++) {
if (k == i || k == j) {
continue;
}
for (int h = 65; h <= 68; h++) {
if (h == i || h == j || h == k) {
continue;
}
System.out.print((char)i+” “);
System.out.print((char)j+” “);
System.out.print((char)k+” “);
System.out.print((char)h+” “);
System.out.println();
}
}
}
}