荣耀8.20笔试
第一题：思路：简单模拟即可
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
in.nextLine();
String str = in.nextLine();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < n; i += 9) {
StringBuilder temp = new StringBuilder(str.substring(i, i + 9));
if (str.charAt(i) == 0) {
sb.append(temp);
} else {
sb.append(temp.reverse());
}
sb.append(" ");
}
} 第二题：思路：正则匹配+优先级队列排序 public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
sc.nextLine();
TreeSet<Pair> ts = new TreeSet<>((a, b) -> {
if (a.timestamp.equals(b.timestamp)) {
if (a.str.length() == b.str.length()) {
return a.str.compareTo(b.str);
} else {
return a.str.length() - b.str.length();
}
} else {
return a.timestamp.compareTo(b.timestamp);
}
});
for (int i = 0; i < n; i++) {
String str = sc.nextLine();
String regex = "[0-9]{4}[-][0-9]{2}[-][0-9]{2}[T][0-9]{2}[:][0-9]{2}[:][0-9]{2}";
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(str);
String timestamp = null;
if (m.find()) {
timestamp = m.group();
}
ts.add(new Pair(str, timestamp));
}
for (Pair p : ts) {
System.out.println(p.str);
}
}
static class Pair {
String str;
String timestamp;
Pair(String str, String timestamp) {
this.str = str;
this.timestamp = timestamp;
} @Override public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Pair pair = (Pair) o;
return pair.str.equals(str) &&
pair.timestamp.equals(timestamp);
} @Override public int hashCode() {
return Objects.hash(str, timestamp);
}
} 第三题：暴力回溯只过了一半，思路：对于每一个数，遍历队伍的每一行看能不能放，最后新建一行并且加入。 static List<List<Integer>> res = new ArrayList<>();
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String s = in.nextLine();
String[] strs = s.split(", ");
int[] nums = new int[strs.length];
for (int i = 0; i < strs.length; i++) {
nums[i] = Integer.parseInt(strs[i]);
}
Arrays.sort(nums);
List<List<Integer>> rows = new ArrayList<>();
backTrack(rows, nums, 0);
System.out.println("lenth:" + nums.length / res.size());
for (List<Integer> r : res) {
System.out.println(r);
}
}
static void backTrack(List<List<Integer>> rows, int[] nums, int index) {
if (index == nums.length) {
if (res.size() == 0 ||( rows.size() < res.size())) {
res = new ArrayList<>();
if (check(rows)) {
for (List<Integer> row : rows) {
res.add(new ArrayList<>(row));
}
}
}
return;
}
int num = nums[index];
for (int i = 0; i < rows.size(); i++) {
List<Integer> row = rows.get(i);
if (row.size() > 1) {
int last = row.get(row.size() - 1);
int preLast = row.get(row.size() - 2);
if (num - last != last - preLast) {
continue;
}
}
if (row.get(0) == num) continue;
row.add(num);
backTrack(rows, nums, index + 1);
row.remove(row.size() - 1);
}
rows.add(new ArrayList<>());
rows.get(rows.size() - 1).add(num);
backTrack(rows, nums, index + 1);
rows.remove(rows.size() - 1);
}
static boolean check(List<List<Integer>> rows) {
int n = rows.get(0).size();
for (int i = 1; i < rows.size(); i++) {
if (rows.get(i).size() != n) return false;
}
return true;
} 
