two pointers solution
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \nTwo pointers \n# Comple
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\nTwo pointers \n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\nO(nlogn)\n\n\n# Code\n```\nclass Solution {\npublic:\n    int countPairs(vector<int>& nums, int target) {\n     \n    sort(nums.begin(), nums.end());\n            int ans = 0;\n    int n = nums.size();\n    int l = 0, h = n - 1;\n    while (l < h) {\n        if (nums[l] + nums[h] < target) {\n            ans += h - l;\n            l++;\n        } else {\n            h--;\n        }\n    }\n    \n    return ans;\n    }\n};\n```
['C++']