Two Sum II - Input Array Is Sorted

Optimized

#include <bits/stdc++.h>
using namespace std;
 vector<int> twoSum(vector<int>& numbers, int target) {
        int n=numbers.size();
        int start=0;
        int end=n-1;
        int sum;
        while(start<end){
            sum=numbers[start]+numbers[end];// to keep track of sum with changing pointers
            if(target==sum)
                return {start+1,end+1};//as the array is one indexed
            else if(sum<target)
                start++;
            else end--; 
            }
        return {};

    }
int main()
{
        int n;
        cin >> n;
        vector<int> nums(n);
        for(auto&it:nums){
            cin >> it;
        }
        int target;
        cin >> target;
        vector<int> indexes;
        indexes = twoSum(nums, target);
        for (auto &it:indexes){
            cout << it<<" ";
        }
            return 0;
}

References

• Question This solution is an extension to the two sum problem and hence the two sum solutions can be applied here too.As here the array is sorted hence binary search or the other approaches in like two pointers make sense.

• Brute force and hashmap approach in two sum can be applied here too.

All approaches