1099. Two Sum Less Than K.md

1099. Two Sum Less Than K, easy, locked, freq: 5.%, acceptance: 62.0%

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's not possible to get a pair sum less that 15.

Note:

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

// 0ms, 100%
class Solution {
public:
    int twoSumLessThanK(vector<int>& A, int K) {
        sort(A.begin(), A.end());
        int i = 0, j = A.size()-1;
        int res = -1;
        while (i < j) {
            int v = A[i] + A[j];
            if (v < K) {
                res = max(res, v);
                i++;
            } else {
                j--;
            }
        }
        return res;
    }
};