9月25快手笔试

第一题

```
import java.util.*;

public class Main {



    public static void main(String[]args){
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();
        int data[]=new int[n];
        for(int i=0;i<n;i++)data[i]=in.nextInt();
        System.out.println(f(data,n));
    }

    public static long f(int data[],int len){
        if(len==1)return 0;
        long rel=0;
        int low=0;int hi=len-1;
        long count1=0,count2=0;
        while(low<=hi){
            while(count1==0||count1<count2){
                count1+=data[low++];
            }
            while(count2==0||count1>count2){
                count2+=data[hi--];
            }
            if(count1==count2){
                if(count1>rel)rel=count1;
                count1+=data[low++];
            }

        }
        return rel;
    }
}

import java.util.Scanner;

public class Main2 {

    public static void main(String[]args){
        Scanner s=new Scanner(System.in);
        String data1[]=s.nextLine().split(" ");
        String data2[]=s.nextLine().split(" ");
        int pre[]=new int[data1.length];
        int in[]=new int[data2.length];
        for(int i=0;i<data1.length;i++)pre[i]=Integer.valueOf(data1[i]);
        for(int i=0;i<data2.length;i++)in[i]=Integer.valueOf(data2[i]);
        f(pre,in);
    }


    public static  void f(int [] pre,int [] in) {
        if (pre.length == 0 || in.length == 0) {
            return ;
        }
        int rel[]=new int[pre.length];
        dfs(pre, 0, pre.length - 1, in, 0, in.length - 1,rel);
        for(int i:rel)
            System.out.print(i+" ");
    }
    public static void dfs(int [] pre,int pstart, int pend, int [] in, int istart, int iend,int []rel) {
        if (pstart > pend || istart > iend) {
            return ;
        }
        int sum=0;
        for(int i=pstart+1;i<=pend;i++)sum+=pre[i];
        for(int i = istart; i <= iend; i++)
            if(in[i] == pre[pstart]){
                 rel[i]=sum;
                 dfs(pre, pstart + 1, pstart + i - istart, in, istart, i - 1,rel);
                 dfs(pre, i - istart + pstart + 1, pend, in, i + 1, iend,rel);
            }
        return ;
    }
}

```