普通双指针

class Solution {
public:
    vector<int> findNumbersWithSum(vector<int>& nums, int sum) {
        vector<int> res;

        for(int i=0;i<nums.size();i++){
            int j=i+1;
            for(;j<nums.size();j++){
                if(nums[i]+nums[j]==sum){
                    res.push_back(nums[i]);
                    res.push_back(nums[j]);
                    return res;
                }
            }
        }

        return {};
    }
};

对撞双指针

class Solution {
public:
    vector<int> findNumbersWithSum(vector<int>& nums, int target) {
        sort(nums.begin(),nums.end());
        for(int i=0;i<nums.size();){
            for(int j=nums.size()-1;i<j;){
                if(nums[i]+nums[j]<target) i++;
                else if(nums[i]+nums[j]>target) j--;
                else if(nums[i]+nums[j]==target){
                    nums.clear();
                    nums.push_back(nums[i]);
                    nums.push_back(nums[j]);
                    return nums;
                }
            }
        }
        return {};
    }
};