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小Q最近遇到了一个难题：把一个字符串的大写字母放到字符串的后面，各个字符的相对位置不变，且不能申请额外的空间。
你能帮帮小Q吗？

输入描述:
输入数据有多组，每组包含一个字符串s，且保证:1<=s.length<=1000.

输出描述:
对于每组数据，输出移位后的字符串。

输入例子1:
AkleBiCeilD

输出例子1:
kleieilABCD

思路：

• 从头到尾遍历，遇到大写字母后跟小写字母的情况，互换两者位置，这样每遍历一次，可将大写字母统一后移一位（除了已满足要求的大写字母）；
• 按照每个字符串字母组合的特点进行多次循环遍历，直到满足题意。

package Problems;


import java.util.Scanner;

public class Move {

    public int firstBig(String s) {
        int len = s.length();
        int index = 0;
        for (int i = 0; i < len; i++) {
            if (s.charAt(i) >= 'A' && s.charAt(i) <= 'Z') {
                index = i;
                break;
            }
        }
        return index;
    }

    public String moveIt(String s) {
        char[] charArray = s.toCharArray();
        int count = s.length() - firstBig(s);
        while (count > 0) {
            count--;
            for (int i = 0; i < charArray.length - 1; i++) {
                if (charArray[i] >= 'A' && charArray[i] <= 'Z' && charArray[i + 1] > 'Z') {
                    char temp = charArray[i];
                    charArray[i] = charArray[i + 1];
                    charArray[i + 1] = temp;
                }
            }
        }
        String res = new String(charArray);
        return res;
    }

    public static void main(String[] args){
        Move move = new Move();
        Scanner input = new Scanner(System.in);
        String str = input.next();
        System.out.println(move.moveIt(str));
    }
}

几个测试用例

public class MoveTest {

    Move move = new Move();
    String result = "";

    @Test
    public void all_chars_are_small() {
        result = move.moveIt("abcde");
        assertEquals("abcde", result);
    }

    @Test
    public void chars_with_one_big() {
        result = move.moveIt("aBcde");
        assertEquals("acdeB", result);
    }

    @Test
    public void chars_with_four_bigs() {
        result = move.moveIt("AkleBiCeilD");
        assertEquals("kleieilABCD", result);
    }

     @Test
    public void chars_with_many_bigs() {
        result = move.moveIt("hxKLAGLLzPyTxsFsrUnnSKQBHdQQrOyaEYJ" +
                "RgiJbHIDXFcQkFmIhPNKIBfHxXDBdKAvgZiBLVwnlxJAHmttsSJ" +
                "kZhSmQneNVoKoIYZRjPqsrFFaaqZbyNyeRjVKVFrCGdfycidTqb" +
                "yQcpAtdRGzzBAaKoqybWMOyhrCQdwcRwQQpQavTnAbjriVwxJOr" +
                "TYJVGYSWzKYeNAGqBzkJLucabNYvyVFxAGKLfqHXNttaqZfncEd" +
                "TroGMzZnDbvZBBaRbJvuYIvlWrKaaGrvtyxrsCUOqxdwCrmVEeD" +
                "rLKZKFJVRmrLsmbmOGUJyfdZIrFhuSwJQGRTYMLxKQNMaCavatl" +
                "QIRZmFQvyWgQTVENxUcPKQCaUQbjyfaNuwoNdTBNldgrtPUcQod" +
                "qsuJOdDpUczJWCZaasDdEYJkvituMHrCmZQSlRjIefVisatIUtf" +
                "xBeKnHPyvWUKzRliFsYWgeXogiEgXDbfxAybwFuqFyEvjfIHEPD" +
                "PKqEiGUtZhdDIDBGKpvBFyqHeEEhAToAbqHEpIdIhIGBtWjGHiQ" +
                "RctZxQQYkfFoWUbqZyIcjRPQBilHrnqNBzFmoRUYCSrGkawJCcO" +
                "rMceegISpIpSGVjbngWVMTYtGoAlQFPFyOFAxndJZNfKDTwFIx" +
                "isKTjyjchidXpYgLfoBOLriuIAHmAbQwoHBgbdUYBHlDQGZJAS" +
                "sHszOEPthLVnYbNqWegmONexfdsTVYHgtDmlyugefOBsqmgNDB" +
                "oxkkhVHfvrYooVOyxDJQJLjYSngksbTopoPJFsKQzHePLukXyYTYCeW");
        assertEquals("hxzyxssrnndryagibckmhfxdvgiwnlxm" +
                "ttskhmneoojqsraaqbyyejrdfycidqbycptdzzaoqybyhrdw" +
                "cwpavnbjriwxrzeqzkucabvyxfqttaqfncdroznbvabvuvlra" +
                "arvtyxrsqxdwrmermrsmbmyfdrhuwxaavatlmvygxcabjyfauw" +
                "odldgrtcodqsudpczaasdkviturmljefisattfxenyvzlisgeog" +
                "igbfxybwuqyvjfqithdpvyqehobqpdhtjictxkfobqycjilrnqzm" +
                "orkawcrceegppjbngtolyxndfwxisjyjchidpgforiumbwogbdlss" +
                "zthnbqegmexfdsgtmlyugefsqmgoxkkhfvrooyxjngksboposzeuk" +
                "yeKLAGLLPTFUSKQBHQQOEYJRJHIDXFQFIPNKIBHXDBKAZBLVJAHSJ" +
                "ZSQNVKIYZRPFFZNRVKVFCGTQARGBAKWMOCQRQQQTAVJOTYJVGYSWK" +
                "YNAGBJLNYVFAGKLHXNZETGMZDZBBRJYIWKGCUOCVEDLKZKFJVRLOG" +
                "UJZIFSJQGRTYMLKQNMCQIRZFQWQTVENUPKQCUQNNTBNPUQJODUJWC" +
                "ZDEYJMHCZQSRIVIUBKHPWUKRFYWXEXDAFFEIHEPDPKEGUZDIDBGKB" +
                "FHEEATAHEIIIGBWGHQRZQQYFWUZIRPQBHNBFRUYCSGJCOMISISGVW" +
                "VMTYGAQFPFOFAJZNKDTFIKTXYLBOLIAHAQHBUYBHDQGZJASHOEPLV" +
                "YNWONTVYHDOBNDBVHYVODJQJLYSTPJFKQHPLXYTYCW", result);
    }

    @Test
    public void chars_with_one_big_in_first() {
        result = move.moveIt("FIuNrJGoGqnPTnuMuUQCpSXwCWFdWljPPcAteMPbkxoCBiPcabpssTedsrfgycuiBuWXZTakaJqKEjxJNzUTIRbhgvFVKpwJjoYREJfBlLTgO ");
        assertEquals("uroqnnuupwdljctebkxoicabpssedsrfgycuiuakaqjxzbhgvpwjoflgFINJGGPTMUQCSXCWFWPPAMPCBPTBWXZTJKEJNUTIRFVKJYREJBLTO ", result);
    }


}