题解 | #MP3光标位置#
MP3光标位置
https://www.nowcoder.com/practice/eaf5b886bd6645dd9cfb5406f3753e15
看题解写得都花里胡哨的，实际上只需要维护两个变量，cur指向当前选择，top指向当前列表顶部，两者关系cur - top < 4，只需要在up和down的时候注意下两者关系就行了
import java.io.IOException;
import java.util.*;
public class Main {
public static void main(String[] args) throws IOException {
Scanner scanner = new Scanner(System.in);
int n = Integer.parseInt(scanner.nextLine());
char[] commands = scanner.nextLine().toCharArray();
int top = 1;
int cur = 1;
for (char command : commands) {
switch (command) {
case 'U':
if (cur == 1) {
cur = n;
if (cur > 4) {
top = cur - 3;
} else {
top = 1;
}
} else {
cur--;
if (top > cur) {
top = cur;
}
}
break;
case 'D':
if (cur == n) {
top = cur = 1;
} else {
cur++;
if (cur > top + 3) {
top++;
}
}
break;
}
}
int max = Math.min(top + 3, n);
for (int i = top; i <= max; i++) {
System.out.print(i);
if (i != max) {
System.out.print(" ");
}
}
System.out.println();
System.out.println(cur);
}
}
