题解 | #环形数组的连续子数组最大和#

import java.util.*;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] nums = new int[n];
        for (int i = 0; i < n; i++) {
            nums[i] = sc.nextInt();
        }
        int[] dpMax = new int[n];
        int[] dpMin = new int[n];
        int sum = nums[0];
        int maxVal = nums[0];
        int minVal = nums[0];
        dpMax[0] = nums[0];
        dpMin[0] = nums[0];
        for (int i = 1; i < n; i++) {
            dpMax[i] = Math.max(dpMax[i - 1] + nums[i], nums[i]);
            maxVal = Math.max(maxVal, dpMax[i]);
            dpMin[i] = Math.min(dpMin[i - 1] + nums[i], nums[i]);
            minVal = Math.min(minVal, dpMin[i]);
            sum += nums[i];
        }
        if (maxVal > 0) System.out.println(Math.max(maxVal, sum - minVal));
        else System.out.println(maxVal);
    }
}