02-04 project euler 223 and 224 How many barely acute triangles are there with perimeter ≤ 25,000,000? 数学 APT NPT
01-18 Educational Codeforces Round 122 E(最小生成树)F(树,数学,树链剖分,线段树,Link/Cut tree) 数学 树 线段树 最小生成树 Link/Cut tree 动态树