Index By Type

Pro.ID	Problem Title	Difficulty	Notes
1027	Ignatius and the Princess II	Difficulty: 1	Notes:
1085	Holding Bin-Laden Captive!	Difficulty: 1	Notes:
1100	Trees Made to Order	Difficulty: 3	Notes:
1153	Magic Bitstrings	Difficulty: 1	Notes:
1171	Big Event in HDU	Difficulty: 1	Notes:
1261	字串数	Difficulty: 2	Notes:
1294	Rooted Trees Problem	Difficulty: 4	Notes:
1398	Square Coins	Difficulty: 1	Notes:
1465	不容易系列之一	Difficulty: 1	Notes:
1492	The number of divisors(约数) about Humble Numbers	Difficulty: 1	Notes:
1510	White Rectangles	Difficulty: 2	Notes:
1521	排列组合	Difficulty: 2	Notes:
1570	A C	Difficulty: 1	Notes:
1716	排列2	Difficulty: 1	Notes:
1799	循环多少次？	Difficulty: 2	Notes:

Combinatorics