LeetCode "Closest Binary Search Tree Value II"

I made it too complicated first.. It is really simply if full-tree in-order traversal is allowed.

class Solution
{
int inx, sofar; // closest
bool bleft; // target on left of closest
vector<int> nums;

void go(TreeNode *p, double target)
{
if (!p) return;
go(p->left, target);
nums.push_back(p->val);
if (abs(sofar - target) > abs(p->val - target))
{
inx = nums.size() - 1;
sofar = p->val;
bleft = target < p->val;
}
go(p->right, target);
}
public:
vector<int> closestKValues(TreeNode* root, double target, int k)
{
sofar = std::numeric_limits<int>::min();
go(root, target);

size_t len = nums.size();
int l = bleft ? inx - 1: inx;
int r = bleft ? inx : inx + 1;

vector<int> ret;
while (k--)
{
if (l < 0)
{
ret.push_back(nums[r ++]);
}
else if (r == len)
{
ret.push_back(nums[l --]);
}
else
{
double succ_diff = abs(nums[r] - target);
double pred_diff = abs(nums[l] - target);
if (succ_diff < pred_diff)
ret.push_back(nums[r++]);
else
ret.push_back(nums[l--]);
}
}
return ret;
}
};

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