Method pop

Data Structures/Persistent Queue.cpp:79–85

    cur++;
  }
  T pop(int r) { // pops the top element of the rth queue and returns the popped element
    st.upd(r, L[r], 0);
    L[cur] = L[r] + 1;
    R[cur] = R[r];
    cur++;
    return st.get_val(r, L[r]);
  }
};

int32_t main(){