寒假

1 G - Greg and Array CodeForces - 296C 差分+线段树 

2 欧拉函数与中国剩余定理

3 Obtain The String CodeForces - 1295C binary_search+思维  

4 V - Infinite Prefixes CodeForces - 1295B math

5 N - Aroma's Search CodeForces - 1293D math+greedy

6 Xor Path 牛客，HPU--C--LCA

7 U - Obtain a Permutation CodeForces - 1294E 思维 

8 D. Minimax Problem Codeforces 1288D binary_search+二进制

9 -----差分简介------

10ATcoder E - Flatten 质因子分解求LCM 

11C - Dr. Evil Underscores CodeForces - 1285D 二进制 

12B - Fadi and LCM CodeForces - 1285C 质因子 

13C - Long Beautiful Integer codeforces 1269C 构造 

14 线段树模板，区间（乘法+加法）