4. Turn your service into a product
What is a stream?，更多细节参见爱思助手下载最新版本
。同城约会对此有专业解读
float r_sequence(int x, int y)
if (right - left <= 1) return; // 只有一个元素，无需排序，更多细节参见同城约会
2-phase A* already uses many heuristics which don't always create an optimal route and still 5-10x slower.