Set Difference
And Or Union
Codeforces Round #703 (Div. 2) C1. Guessing the Greatest (easy version)
Codeforces Round #708 (Div. 2) C2. k-LCM (hard version)
CodeCraft-21 and Codeforces Round #711 (Div. 2) C. Planar Reflections
Codeforces Round #712 (Div. 1) A. Balance the Bits
Educational Codeforces Round 107 (Rated for Div. 2) D. Min Cost String
Subarray with given XOR
Maximum Area of Triangle!
Maximum Sum Square SubMatrix