题目

import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);String str = sc.nextLine();char[] c = str.toCharArray();int n = c.length;StringBuilder st = new StringBuilder();int i = 0;while(i<n) {char x = c[i];if(x>='a'&&x<='z') {if(i == 0 || c[i-1] == ' ') {x^=32;}st.append(x);i++;}else if(x==' ') {st.append(x);while(c[i] == ' ')i++;}else {if(i>0&&c[i-1]>='a'&&c[i-1]<='z')st.append('_');st.append(x);if(i+1<n&&c[i+1]>='a'&&c[i+1]<='z')st.append('_');i++;}}System.out.println(st);sc.close();}
}