1、线段总长度（a）  public class Main3 {    public static void main(String[] args) {        Scanner sc = new Scanner(System.in);        int n=sc.nextInt();        String[] a=new String[n];        int l,r;        Map<Integer,Integer> map=new HashMap<>();        for(int i=0;i<n;i++){            a[i]= sc.next();            String[] b=a[i].split(",");            l=Integer.parseInt(b[0]);            r=Integer.parseInt(b[1])-1;            for(int j=l;j<=r;j++){                map.put(j,map.getOrDefault(j,0)+1);            }        }        int count=0;        for(Map.Entry<Integer,Integer> entry:map.entrySet()){            if(entry.getValue()==1) count++;        }        System.out.println(count);    }} 2、偶数在前奇数在后（a）  public class Main1 { public static void main(String[] args) {        Scanner sc = new Scanner(System.in); int n=sc.nextInt();        String s=sc.next();        String[] sp=s.split(","); int[] a=new int[n];        String res=""; for(int i=0;i<n;i++){            a[i]=Integer.parseInt(sp[i]);        }        ArrayList<Integer> list=new ArrayList<>(); for(int j=0;j<n;j++){ if(a[j]%2==0){                list.add(a[j]);                a[j]=-1;            }        } for(int j:list){            res+=j+",";        } for(int j=0;j<n;j++){ if(a[j]!=-1){                res+=a[j]+",";            }        }        res=res.substring(0,res.length()-1);        System.out.println(res);    }} 3、搬家（贪心，80%） public class Main2 {    public static void main(String[] args) {        Scanner sc = new Scanner(System.in);        int muscle=sc.nextInt();        int jiaju=sc.nextInt();        int[] s=new int[jiaju];        for(int i=0;i<jiaju;i++) {            s[i]=sc.nextInt();        }        int jiaju2=sc.nextInt();        int[] h=new int[jiaju2];        for(int i=0;i<jiaju2;i++) {            h[i]=sc.nextInt();        }        double[] tanxin=new double[jiaju];        for(int i=0;i<jiaju;i++){            tanxin[i]=(double) s[i]/h[i];        }        Arrays.sort(tanxin);        int cout=0,musclenow=0;        for(int i=jiaju-1;i>=0;i--){            if(musclenow<=musclenow){                if(muscle>=h[i]+musclenow){                    cout+=s[i];                    musclenow+=h[i];                }            }        }        System.out.println(cout);    }}