Method insert

pointersect/pr/cpp/pr.cpp:35–43

associate pidx with gidx

    // associate pidx with gidx
    void insert(int64_t gidx, int64_t pidx) {
        auto iter = table.find(gidx);
        if (iter == table.end()) {
            table[gidx] = std::unordered_set<int64_t>({pidx});
        }
        else {
            table[gidx].insert(pidx);
        }
    }

    // get the pointer to the point index set
    std::unordered_set<int64_t> * get_pidx(int64_t gidx) {