compareCount++;
先理解原理：看动图 + 手动模拟小数组
。业内人士推荐同城约会作为进阶阅读
The A/D bits exist entirely for the operating system's benefit. The Accessed bit tells the OS which pages have been recently used, enabling page replacement algorithms to choose pages to evict when memory runs low. The Dirty bit tells the OS which pages have been modified and must be written back to disk before eviction; clean pages can simply be discarded and re-read from disk later.
乔布斯之所以否决一台触控 Mac，其实是因为他想得会更深远一点：如果要为 Mac 增加触控屏，那必须要围绕全新的「触控」交互，大改整个 Mac 的界面，进一步发挥触屏的价值，要不然就不加。