leetcode918.环形子数组的最大和

参考了灵神的题解，然后只要用动态规划求解子数组的最大和和最小和就可以

class Solution {
    public int maxSubarraySumCircular(int[] nums) {
        int sum = nums[0];
        //变量记录普通子数组的最大和
        int currentMax = nums[0];
        int globalMax = nums[0];
        //变量记录普通子数组的最小和
        int currentMin = nums[0];
        int globalMin = nums[0];

        //动态规划求解普通子数组的最大和和最小和
        for (int i = 1; i < nums.length; i++) {
            sum += nums[i];
            currentMax = Math.max(currentMax + nums[i], nums[i]);
            globalMax = Math.max(globalMax, currentMax);
            currentMin = Math.min(currentMin + nums[i], nums[i]);
            globalMin = Math.min(globalMin, currentMin);
        }
        return sum == globalMin ? globalMax : Math.max(globalMax, sum - globalMin);
    }
}