2012 Asia ChangChun Regional Contest（2013区域赛练习）
去年比赛只去了长春，几乎没做题和看题，今天一个人做了4小时最后出了4题，可惜有一题有思路，最后没时间做了，今年这个实力估计铜都很难保证。
code:https://github.com/9974/2012Region/tree/master/changchun(已更新4424)
4421 2-sat，算很基本的了，用vector写很卡时间，写搓了就会TLE。
4422 模拟 比较水
4424 并查集，是最小生成树的拓展生成树相关问题学习
4427 很清晰的dp，只是写搓了会TLE，本人很搓，T了好几发。
4430 二分，注意要判断加数是否爆long long
| Solved | Pro.ID | Title | Author | Source | (AC/Submit)Ratio |
| 4420 | Alice and Bob | 2012 Asia ChangChun Regional Contest | (36/373)9.65% | ||
 |
4421 | Bit Magic | 2012 Asia ChangChun Regional Contest | (339/1206)28.11% | |
| |
4422 | The Little Girl who Picks Mushrooms | 2012 Asia ChangChun Regional Contest | (331/1018)32.51% | |
| 4423 | Simple Function | 2012 Asia ChangChun Regional Contest | (33/116)28.45% | ||
| |
4424 | Conquer a New Region | 2012 Asia ChangChun Regional Contest | (253/831)30.45% | |
| 4425 | Fantastic Necklace | 2012 Asia ChangChun Regional Contest | (11/124)8.87% | ||
| 4426 | Palindromic Substring | 2012 Asia ChangChun Regional Contest | (46/293)15.70% | ||
| |
4427 | Math Magic | 2012 Asia ChangChun Regional Contest | (292/749)38.99% | |
| 4428 | Polaris of Pandora | 2012 Asia ChangChun Regional Contest | (13/61)21.31% | ||
| 4429 | Split the Rectangle | 2012 Asia ChangChun Regional Contest | (62/177)35.03% | ||
| |
4430 | Yukari's Birthday | 2012 Asia ChangChun Regional Contest | (365/1772)20.60% |