Mobile contact synchronous with cloud server

Mobile industry promotes new products every recent year. It is reported that consumers in high-income countries typically replace their mobile phones at intervals of between 12 and 18 months. How to transfer data from one mobile to another and how to share data between different mobile apps are taken into consideration. We build a cloud service to combine contacts from different mobiles and synchronize contacts in different mobiles. Some algorithms and data structures are designed to meet the needs of data combination and synchronization. The result shows that our method can provide more efficient result than other solutions.