1755. Closest Subsequence Sum

class Solution {
public:
   map<int, int> m;
int sum[1000005];
int sum2[1000005];
int p;
void fun(int n, int i, int s,vector<int>& nums, int* sum)
{
	if (m[s] == 0)
	{
		m[s] = 1;
		sum[p++] = s;
	}
	
	for (int j = i + 1; j < n; j++)
	{
		fun(n, j, s+nums[j], nums, sum);
	}
}
    
    int minAbsDifference(vector<int>& nums, int goal)
{
	int ans = INT_MAX;
	int n = nums.size()/2;
	p = 0;
	for (int i = 0; i < n; i++)
	{
		fun(n, i, nums[i], nums, sum);
	}
	int p1 = p;
	m.clear();
	for (int i = 0; i < p1; i++)
	{
		ans = min(ans, abs(sum[i] - goal));
	}
	p = 0;
	for (int i = n; i < nums.size(); i++)
	{
		fun(nums.size(), i, nums[i],nums, sum2);
	}
	for (int i = 0; i < p; i++)
	{
		ans = min(ans, abs(sum2[i] - goal));
	}

	sort(sum, sum + p1);
	
	// 1 2 5 6
	for (int i = 0; i < p; i++)
	{
		int x = sum2[i];

		int l = 0;
		int r = p1;

		while (l <= r)
		{
			int mid = (l + r) / 2;
			ans = min(ans, abs(sum[mid] + x - goal));
			if (sum[mid] + x > goal)
			{
				r = mid - 1;
			}
			else if (sum[mid] + x < goal)
			{
				l = mid + 1;
			}
			else
			{
				return 0;
			}
		}
	}
	return ans;
}


};