986

class Solution {
public:
    vector<vector<int>> intervalIntersection(vector<vector<int>>& A, vector<vector<int>>& B) {
        int a, b, a_start, a_end, b_start, b_end;
        a = b = 0;
        vector< vector<int> > res;
        while(a < A.size() && b < B.size()){
            a_start = A[a][0], a_end = A[a][1];
            b_start = B[b][0], b_end = B[b][1];

            if(a_start <= b_end && b_start <= a_end){
                int left = max(a_start, b_start);
                int right = min(a_end, b_end);
                res.push_back(vector<int> {left, right});
            }

            if(a_end <= b_end)
                a++;
            else
                b++;
        }
        return res;
    }
};