python3

class Solution:
    def purchasePlans(self, nums: List[int], target: int) -> int:
        mod = 1000000007 
        res = 0
        
        nums = [i for i in nums if i < target]
        n = len(nums) - 1
        m = 0
        nums.sort()
        while(m < n): 
            if nums[n] + nums[m] <= target: 
                res += n - m
                m += 1
            if nums[n] + nums[m] > target: 
                n -= 1
                
        return res % mod

java

class Solution {
    public int purchasePlans(int[] nums, int target) {
        int res = 0, s = 0, len = nums.length - 1;
        Arrays.sort(nums);
        while (s < len) {
            while(len >= 0 && (nums[s] + nums[len]) > target) 
                  len--;
                  if(s < len) 
                      res += (len - s);
                  res %= 1000000007;
                  s++ ;
        }
        return res;
    }
}