双指针

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        int i=0,j=numbers.size()-1;
        while(i<j){
            if(numbers[i]+numbers[j]==target)return{i+1,j+1};
            else if(numbers[i]+numbers[j]>target)j--;
            else i++;
        }
        return{};
    }
};

二分

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        int l=0,r=numbers.size()-1;
        while(l<r){
            int mid=(l+r)>>1;
            if(numbers[l]+numbers[mid]>target)r=mid-1;
            else if(numbers[r]+numbers[mid]<target)l=mid+1;
            else if(numbers[l]+numbers[r]>target)r--;
            else if(numbers[l]+numbers[r]<target)l++;
            else return{l+1,r+1};
        }
        return{};
    }
};