给定分治法实现的最大连续子数组和C++代码，下列说法错误的是？

int crossSum(vector<int>& nums, int left, int mid, int right) {
    int leftSum = INT_MIN, rightSum = INT_MIN;
    int sum = 0;
    for (int i = mid; i >= left; i--) {
        sum += nums[i];
        leftSum = max(leftSum, sum);
    }
    sum = 0;
    for (int i = mid + 1; i <= right; i++) {
        sum += nums[i];
        rightSum = max(rightSum, sum);
    }
    return leftSum + rightSum;
}

int helper(vector<int>& nums, int left, int right) {
    if (left == right)
        return nums[left];
    int mid = left + (right - left) / 2;
    int leftMax = helper(nums, left, mid);
    int rightMax = helper(nums, mid + 1, right);
    int crossMax = crossSum(nums, left, mid, right);
    return max({leftMax, rightMax, crossMax});
}

int maxSubArray(vector<int>& nums) {
    return helper(nums, 0, nums.size() - 1);
}