POJ上的DP分类：容易：1018,1050,1083,1088,1125,1143,1157,1163,1178,1179,1189,1208,1276,1322,1414,1456,1458,1609,1644,1664,1690,1699,1740(博弈),1742,1887,1926(马尔科夫矩阵，求平衡）,1936,1952,1953,1958,1959,1962,1975,1989,2018,2029,2039,2063,2081,2082,2181,2184,2192,2231,2279,2329,2336,2346,2353,2355,235