Maximum Sum Queries — C++

// Time:  O(nlogn + mlogm + mlogn)
// Space: O(n + m)

// sort, mono stack, binary search
class Solution {
public:
    vector<int> maximumSumQueries(vector<int>& nums1, vector<int>& nums2, vector<vector<int>>& queries) {
        vector<pair<int, int>> pairs;
        for (int i = 0; i < size(nums1); ++i) {
            pairs.emplace_back(nums1[i], nums2[i]);
        }
        sort(begin(pairs), end(pairs));
        vector<tuple<int, int, int>> sorted_queries;
        for (int i = 0; i < size(queries); ++i) {
            sorted_queries.emplace_back(queries[i][0], queries[i][1], i);
        }
        sort(rbegin(sorted_queries), rend(sorted_queries));
        vector<int> result(size(queries));
        vector<pair<int, int>> stk;
        for (const auto& [x, y, i] : sorted_queries) {
            while (!empty(pairs) && pairs.back().first >= x) {
                const auto [a, b] = pairs.back(); pairs.pop_back();
                while (!empty(stk) && stk.back().second <= a + b) {
                    stk.pop_back();
                }
                if (empty(stk) || stk.back().first < b) {
                    stk.emplace_back(b, a + b);
                }
            }
            const auto it = lower_bound(cbegin(stk), cend(stk), pair(y, 0));
            result[i] = it != cend(stk) ? it->second : -1;
        }
        return result;
    }
};