Problem - 1879D - Codeforces
Educational Codeforces Round 155 (Rated for Div. 2)(A~D)(贪心/简单数论/位运算) - 知乎 (zhihu.com)
CF1879D Sum of XOR Functions - XYukari - 博客园 (cnblogs.com)
【位运算】Sum of XOR Functions—CF1879D-CSDN博客