输出 n 层的三角形，倒三角和叠在一起的沙漏

void printTriangle(int32_t layerNum)
{
    if (layerNum < 1){
        return;
    }
    
    for (int32_t currentNum = 1, spaceWide  = layerNum - 1;
         spaceWide != 0;
         --spaceWide, ++currentNum){
        std::printf("%*s", spaceWide, "");
        std::printf("%s
", std::string((currentNum * 2 - 1), '*').data());
    }
}

void printInvertedTriangle(int32_t layerNum)
{
    if (layerNum < 1){
        return;
    }
    
    for (int32_t currentNum = layerNum - 1, spaceWide  = 0;
         currentNum != 0;
         ++spaceWide, --currentNum){
        std::printf("%*s", spaceWide, "");
        std::printf("%s
", std::string((currentNum * 2 - 1), '*').data());
    }
}

void printfHourGlass(int32_t num)
{
    if (num < 1){
        return;
    }
    
    for (int32_t currentNum = num - 1, spaceWide  = 0;
         currentNum != 0;
         ++spaceWide, --currentNum){
        std::printf("%*s", spaceWide, "");
        std::printf("%s
", std::string((currentNum * 2 - 1), '*').data());
    }
    
    for (int32_t currentNum = 3, spaceWide  = num - 3;
         spaceWide != 0;
         --spaceWide, ++currentNum){
        std::printf("%*s", spaceWide, "");
        std::printf("%s
", std::string((currentNum * 2 - 3), '*').data());
    }
}