第一道题：说给N个不同的字符，求长度为L的时候有多少种方法。当总数大于1000000007的时候，需要求模。
举例 当N=2（假设不同字符为a,b）长度为3（a,b,aa,ab,bb,ba,aaa,aab,aba,abb,bbb,bba,bab,baa）=14
大概就是求(A N1 )得一次方到L次方的和。
楼主先用了Math.pow() 过了27% 发现溢出
然后用了 BigDecimal 过了34%
后面使用了 快速幂全AC
bigcmals 
第二道题
说给一个字符串，对字符串进行处理和处理后每行的长度L。
每行的尽可能包含多的单词，单词之间或者尾部不足要用“*”补充，要是一样有两个或者两个单词以上，要求最左边的单词和最后边单词对齐，一行的单词之间的“*”要尽可能均分布，如果不能的话，左边可以比右边多1个“*”，最后一行的单词之间只要一个"*"
说明： 就是一行字符串包含多个单词，你需要把单词使用*分开，单词尽可能分布在一行，但是不能完整单词不能换行，每行单词不能超过L。
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String s = scanner.nextLine();
String[] str = s.split(",");
int n = str.length;
int l = Integer.parseInt(scanner.nextLine());
int begin = 0;
int end = 0;
int preSum = 0;
while (end < n){
StringBuilder sb = new StringBuilder();
preSum = 0;
while(end <n && preSum + end -begin + str[end].length()<l){
preSum += str[end].length();
end++;
}
if(end ==n){
break;
}
System.out.println(reBuildStr(str,begin,end,l,preSum));
begin = end;
}
System.out.println(mergeEnd(str,begin,l));
}
private static String mergeEnd(String[] str, int begin, int l) {
StringBuilder res = new StringBuilder();
for (int i = begin; i < str.length; i++) {
res.append(str[i]);
res.append("*");
}
if (res.length()>l) {
res.deleteCharAt(res.length()-1);
}else{
while (res.length()<l) {
res.append("*");
}
}
return res.toString();
}
private static String reBuildStr(String[] str, int begin,int end,int l,int preSum) {
StringBuilder sb = new StringBuilder();
int curSum = end - begin;
if(curSum == 1){
sb.append(str[end-1]);
for (int i = 0; i < l -str[begin].length();i++) {
sb.append("*");
}
return sb.toString();
}
int avg = (l-preSum) / (curSum -1);
int remain = (l-preSum) % (curSum -1);
for(int i = begin;i<begin +remain;i++){
sb.append(str[i]);
for(int j = 0;j<avg +1;j++){
sb.append("*");
}
}
for(int i = begin + remain;i< end -1;i++){
sb.append(str[i]);
for (int j = 0; j < avg;j++) {
sb.append("*");
}
}
sb.append(str[end-1]);
return sb.toString();
}
} 第三题：
输入学生信息 包括姓名，语文，数学，英语成绩。
要求：
1.将每门课成绩都合格的输出。
2.按照总分、语文、数学、英语排序输出。（先看总分 ，总分想等看语文成绩、一依次类推）
3.输出录取名单。只要前三名，如果某一名有多位，都输出。
4.成绩相同的，名字按照ASCII码排序从小到大输出。
5.名字不会有重复的，所有成绩都合法。
public class Main3 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
LinkedList<Student> list = new LinkedList<>();
LinkedList<Student> no = new LinkedList<>();
int index = 1;
while (scanner.hasNext() && index <=10){
String[] split = scanner.nextLine().split(" ");
index++;
int chin = Integer.parseInt(split[1]);
int math = Integer.parseInt(split[2]);
int english = Integer.parseInt(split[3]);
int score = chin + math + english;
Student s = new Student(split[0], chin,math ,english ,score);
if(chin>=60 && math>=60 && english>=60){
list.add(s);
}else {
no.add(s);
}
}
System.out.println();
Comparator comparator = (o1, o2) -> {
if(o1 instanceof Student && o2 instanceof Student){
Student s1 = (Student) o1;
Student s2 = (Student) o2;
int k = s1.score.compareTo(s2.score);
if (k==0) {
int j = s1.chinese.compareTo(s2.chinese);
if (j ==0) {
int i = s1.math.compareTo(s2.math);
if(i==0){
int m = s1.english.compareTo(s2.english);
if(m==0){
int n = s1.name.toLowerCase().compareTo(s2.name.toLowerCase());
return n == 0 ? 0 :-(n>0 ? 1:-1);
}
return -m;
}
return -j;
}
}
return -k;
}
return 0;
};
TreeSet<Student> tree = new TreeSet(comparator);
tree.addAll(list);
System.out.println("[First round name list]");
for (Student o : tree) {
System.out.println(o.name+" " +o.chinese+" "+o.math+" "+o.english);
}
System.out.println();
int time = 0;
Student cur = null;
System.out.println("[Find name list]");
for (Student o : tree) {
time += 1;
if(time ==1){
System.out.println(o.name+" " +o.chinese+" "+o.math+" "+o.english);
}else if(time <= 3){
if(time == 2){
cur = o;
}
System.out.println(o.name+" " +o.chinese+" "+o.math+" "+o.english);
}else{
if(o!=null && cur.score.equals(o.score) && cur.math.equals(o.math) && cur.chinese.equals(o.chinese) && cur.english.equals(o.english)){
System.out.println(o.name+" " +o.chinese+" "+o.math+" "+o.english);
}else{
return;
}
}
}
}
@Test
public void test(){
System.out.println("simonyin".toLowerCase().compareTo("liutao"));
}
static class Student {
public String name;
public Integer chinese;
public Integer math;
public Integer english;
public Integer score;
public Student(String name, Integer chinese, Integer math, Integer english, Integer score) {
this.name = name;
this.chinese = chinese;
this.math = math;
this.english = english;
this.score = score;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Student student = (Student) o;
return chinese == student.chinese && math == student.math && english == student.english && score == student.score && Objects.equals(name, student.name);
}
@Override
public int hashCode() {
return Objects.hash(name, chinese, math, english, score);
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", chinese=" + chinese +
", math=" + math +
", english=" + english +
", score=" + score +
'}';
}
}
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