题解 | #丢手绢#java

import java.util.Scanner;

public class Main {
    public static void main(String []args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();

        int sum = 0;
        int count = 0;
        int min_mark = 2147483647;
        int left = 0;
        int right = 0;
        int [] shuru = new int[n];
        for(int i = 0;i<n;i++){
            shuru[i] = sc.nextInt();
            sum +=shuru[i];
        }
        double half = sum/2.0;
        
        while(right<2*n-1&&left<n){
           if(count<half){
            count+=shuru[right%n];
            right++;
           }else{
            if(count<min_mark){
                min_mark = count;
                count = count-shuru[left];
                left++;
            }else{
                count = count-shuru[left];
                left++;
            }
           }
        }
        if(sum == 0) System.out.println(0);
        else if(left == 0) System.out.println(sum);
        else System.out.println(sum-min_mark);
    }
}

其中值得注意的是，这是一个圆，可能right比left小。