前缀和 或者 动态规划

前缀

import java.util.Scanner;
import java.util.stream.Stream;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] v = sc.nextLine().split(",");
        int[]p = new int[v.length+1];
        p[0] =  Integer.parseInt(v[0]);
        if(v.length==1) {
            System.out.println(p[0]>0?p[0]:0);
            return;
        }
        for(int i=1;i<v.length;++i) {
            p[i] = p[i-1]+Integer.parseInt(v[i]);
        }
        int max = 0;
        for(int i=1;i<v.length;++i) {
           "" 暴力解决 时间复杂度为 O(N^2) ""
        }
        System.out.println(max);

    }
    public static int max(Integer... a) {
        return Stream.of(a).max(Integer::compare).get();
    }



}

方法二：
动态规划

import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.Stream;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] v = sc.nextLine().split(",");
        int[]dp = new int[v.length+1];
        dp[0] =  Integer.parseInt(v[0]);
        if(v.length==1) {

            System.out.println(dp[0]>0?dp[0]:0);
            return;
        }

        for(int i=1; i<v.length;++i) {
            int cur = Integer.parseInt(v[i]);
            dp[i] = max( dp[i-1]+cur, cur);
        }
        System.out.println(max(dp));



    }
    public static int max(Integer... a) {
        return Stream.of(a).max(Integer::compare).get();
    }
    public static int max(int[] a) {
        return Arrays.stream(a).max().getAsInt();
    }


}