2824. Count Pairs Whose Sum is Less than Target

Given a 0-indexed integer array nums of length n and an integer target, return the number of pairs (i, j) where 0 <= i < j < n and nums[i] + nums[j] < target.

class Solution {
public:
    int countPairs(vector<int>& nums, int target) {
        int res = 0;
        for(int i = 0; i < nums.size(); i++) {
            for(int j = i + 1; j < nums.size(); j++) {
                if(nums[i] + nums[j] < target) res += 1;
            }
        }
        return res;
    }
};