1099.txt

Given an array A of integers and integer K, return the maximum S such that there exists i < j with A[i] + A[j] = S and S < K. If no i, j exist satisfying this equation, return -1.

 

Example 1:

Input: A = [34,23,1,24,75,33,54,8], K = 60
Output: 58
Explanation: We can use 34 and 24 to sum 58 which is less than 60.
Example 2:

Input: A = [10,20,30], K = 15
Output: -1
Explanation: In this case it is not possible to get a pair sum less that 15.
 

Constraints:

1 <= A.length <= 100
1 <= A[i] <= 1000
1 <= K <= 2000







class Solution {
public:
    int twoSumLessThanK(vector<int>& A, int K) {
        sort(A.begin(),A.end());
        int l=0,r=A.size()-1;
        int res=-1;
        
        while(l<r){
            if(A[l]+A[r]>=K){
                r--;
            }
            else{
                res=max(res,A[l]+A[r]);
                l++;
            }
        }
        
        return res;
    }
};