数字的最大连续子数组之和

f(i) = max(f(i-1), a(i))

public int maxSum(int[] nums) {
    if (nums.length == 0) {
        return 0;
    }
    if (nums.length == 1) {
        return nums[0];
    }
    int sumMinus1 = nums[0];
    for (int i=1; i<nums.length; i++) {
        sumMinus1 = Math.max(sumMinus1, nums[i]);
    }
    return sumMinus1;
}