uva202: https://blog.csdn.net/lecholin/article/details/70163148 uva1589: https://blog.csdn.net/qq_42191950/article/details/80945685 https://www.jianshu.com/p/a44d0662a070 uva1339: https://blog.csdn.net/karry_zzj/article/details/72763986 uva489: https…