/* Create Hourglass Pattern Create an hourglass pattern out of numbered triangles as pictured below. The innermost shape is one. The outermost shape should be nine or the maximum you can display in landscape display mode. The outermost shape shares the joining number of the two triangles. All other triangles are complete on both sides surounding a space filled center. https://code.sololearn.com/c1UH5aTK24TR https://www.sololearn.com/post/153188/?ref=app */ #include #include #include #include #include using namespace std; // hourglass vector row generator helper // the idea is given a number N=4, the // pattern is like // 4 // 4 4 // 4 3 4 // 4 3 3 4 // 4 3 2 3 4 // 4 3 2 2 3 4 // i.e take the last digit, the first is // formed by appending the reverse of 1 // digit left of last digit till start to // the right of it. The second row is // formed by appending the // reverse of string starting from last // digit till the first (inclusive to the // right of last digit). // For the next iteration append N-1 to N // including spaces. So now your temporary // number string is "4 3". Using the above // formula the next row is calculated as // follows - last digit = 3. One digit left // of it till the start is 4,so append 4 to // to the right of it and we get "4 3 4". // The next one - reverse from last digit // till start and append to the right of it // So we "4 3" it's reverse is "3 4", // append to the right of last digit 3 and // we get "4 3 3 4". The off(set) variable // takes care of 1 digit left, including // spaces auto hgv_impl = [](auto&& cs, int off=2){ return cs+" "+string(rbegin(cs)+off, rend(cs));}; // generates hourglass vector rows using // the helper function and stores them in // vector for later use auto hgv=[](auto&& cs, auto&& tri, int off=2){tri.emplace_back(hgv_impl(cs, off));}; auto print = [](auto&& start, auto&& stop, size_t w){ for_each(start, stop,[&](auto&& row){ cout << setw(w) << left << row << " " << setw(w) << right << row << "\n";});}; int main() { int sn{3}; cin >> sn; string ns{to_string(sn)}, cs; vector tri{ns, ns+" "+ns}; // generate hourglass pattern and store // it in a vector for (int i = 1; i < sn; ++i){ cs = ns+" "+to_string(sn-i); hgv(cs, tri), hgv(cs, tri, 0); ns = cs; } cout << "\n\n"; // output width field used to left and // right justify each row of hourglass int w {4*sn}; // print the rows of hourglass pattern // and justify the row text first to // left then to right print(begin(tri), end(tri), w); // middle line extra handling, bit ugly string rev{rbegin(cs), rend(cs)}; cout << cs << " " << hgv_impl(rev) + " "+rev <<"\n"; // print in reverse print(rbegin(tri), rend(tri), w); }

[Challenge] Horizontal HourGlass Pattern.cpp