Millions of tourists come here every year to visit the ancient ruins of Angkor Wat, an influx that has helped transform what once resembled a small, laid-back village into a thriving and cosmopolitan town with thumping nightlife and more than 10,000 hotel rooms. But the explosion of the tourism industry here has also done something less predictable. Siem Reap, which had no universities a decade ago, is now Cambodia’s second-largest hub for higher education, after the capital, Phnom Penh. The sons and daughters of impoverished rice farmers flock here to work as tour guides, receptionists, bartenders and waitresses. When their shifts are over, they study finance, English and accounting.