有几道题 小弟真是不会了。。。

Question

1。有1，2，2，3，4，5六个数，要求输出他们组合的全排列，4不能在第三位，5和3不能相邻
2。考勤表id(PK int) name(varchar) time(datetime)，求迟到次数最多的员工的最后一次迟到时间
看到一个帖子上的面试题 我是真算不出了
麻烦高手帮忙讲讲

Answer 1

sql还好说
那个排列的真麻烦
先不用加条件 就把所有可能出现的排序写出来就ok

Answer 2

public class Test3 {   
    // 当前固定部分   
    private String CurFixPart;   
  
    private String PreGenNum;   
  
    public static void main(String[] args) {   
        Test3 t = new Test3();   
        t.GenControll("123456");   
    }   
  
    // 调整字符串s位置pos字符到最前   
    private String shift(String s, int pos) {   
        String newStr;   
        if (s.length() > pos + 1)   
            newStr = s.substring(pos, pos + 1) + s.substring(0, pos)   
                    + s.substring(pos + 1);   
        else  
            newStr = s.substring(pos) + s.substring(0, pos);   
        return newStr;   
    }   
  
    private int Validate(String newNum) {   
        String newGenNum = CurFixPart + newNum;   
        if (Integer.valueOf(newGenNum) <= Integer.valueOf(PreGenNum))   
            return 0;   
        if (newGenNum.substring(2, 3).equals("4")   
                || (newGenNum.indexOf("35") != -1)   
                || (newGenNum.indexOf("53") != -1))   
            return 0;   
  
        PreGenNum = newGenNum;   
        System.out.println("----"+newGenNum);   
         
        return 0;   
    }   
  
 public void GenControll(String Base) {   
        PreGenNum = "0";   
        CurFixPart = "";   
        GenNext(Base, 0);   
    }   
  
    public void GenNext(String varPart, int curPos) {   
        if (varPart.length() == 2) {   
            Validate(varPart);   
            Validate(shift(varPart, 1));   
            return;   
        }   
        // Next Layer   
        String newGen = shift(varPart, curPos);   
        String SavedFixPart = CurFixPart;   
        CurFixPart = CurFixPart + newGen.substring(0, 1);   
        GenNext(newGen.substring(1), 0);   
        CurFixPart = SavedFixPart;   
        // 同层递增   
        if (curPos == varPart.length() - 1)   
            return;   
        GenNext(varPart, curPos + 1);   
           
    }   

Answer 3

第一题：把全排列放进一个hastable中，然后循环，remove.compareto("53")
remove.compareto("4")

Answer 4

第2道：
select top 1 time from test where name =
(select top 1 name from test group by name order by count(*) desc)
order by time desc

Answer 5

select top 1 time
from test
where name in(select name
              from test
              group by name
              having count(time)>=all(select count(time)
                                      from test
                                      group by name))
order by time desc

Answer 6

    Sub Main()        Dim d As New List(Of String)
        Dim num() As Integer = {1, 2, 2, 3, 4, 5}
        For i1 = 0 To 5
            For i2 = 0 To 5
                If i2 = i1 Then Continue For
                If num(i2) = 5 And num(i1) = 3 Then Continue For
                If num(i2) = 3 And num(i1) = 1 Then Continue For
                For i3 = 0 To 5
                    If i3 = i1 OrElse i3 = i2 Then Continue For
                    If num(i3) = 4 Then Continue For
                    If num(i3) = 5 And num(i2) = 3 Then Continue For
                    If num(i3) = 3 And num(i2) = 5 Then Continue For
                    For i4 = 0 To 5
                        If i4 = i1 OrElse i4 = i2 OrElse i4 = i3 Then Continue For
                        If num(i4) = 5 And num(i3) = 3 Then Continue For
                        If num(i4) = 3 And num(i3) = 5 Then Continue For
                        For i5 = 0 To 5
                            If i5 = i1 OrElse i5 = i2 OrElse i5 = i3 OrElse i5 = i4 Then Continue For
                            If num(i5) = 5 And num(i4) = 3 Then Continue For
                            If num(i5) = 3 And num(i4) = 5 Then Continue For
                            For i6 = 0 To 5
                                If i6 = i1 OrElse i6 = i2 OrElse i6 = i3 OrElse i6 = i4 OrElse i6 = i5 Then Continue For
                                If num(i6) = 5 And num(i5) = 3 Then Continue For
                                If num(i6) = 3 And num(i5) = 5 Then Continue For
                                Console.WriteLine(String.Format("{0}-{1}-{2}-{3}-{4}-{5}", num(i1), num(i2), num(i3), num(i4), num(i5), num(i6)))                            Next
                        Next
                    Next
                Next
            Next
        Next    End Sub

Answer 7

如果条件复杂多变的话    Sub Main()        Dim d As New List(Of String)
        Dim num() As Integer = {1, 2, 2, 3, 4, 5}
        For i1 = 0 To 5
            For i2 = 0 To 5
                If i2 = i1 Then Continue For
                For i3 = 0 To 5
                    If i3 = i1 OrElse i3 = i2 Then Continue For
                    For i4 = 0 To 5
                        If i4 = i1 OrElse i4 = i2 OrElse i4 = i3 Then Continue For
                        For i5 = 0 To 5
                            If i5 = i1 OrElse i5 = i2 OrElse i5 = i3 OrElse i5 = i4 Then Continue For
                            For i6 = 0 To 5
                                If i6 = i1 OrElse i6 = i2 OrElse i6 = i3 OrElse i6 = i4 OrElse i6 = i5 Then Continue For                                d.Add(String.Format("{0}-{1}-{2}-{3}-{4}-{5}", num(i1), num(i2), num(i3), num(i4), num(i5), num(i6)))                            Next
                        Next
                    Next
                Next
            Next
        Next        d.AsParallel.Where(Function(s) s(7) <> "4"c And s.IndexOf("3-5") = -1 And s.IndexOf("5-3") = -1).ForAll(Sub(s)
                                                                                                                    Console.WriteLine(s)
                                                                                                                End Sub)
    End Sub