c++使用用空格拼接字符串_accumulate用法
std::accumulate(std::begin(x), std::end(x), string(), [](string &ss, string &s){return ss.empty() ? s : ss + " " + s;})
- ss是初始值 string(),相当于上一个值
- s为当前遍历的元素
std::accumulate(std::begin(x), std::end(x), string(), [](string &ss, string &s){return ss.empty() ? s : ss + " " + s;})