快速幂中都换成加号,初始化是\(0\).
ll q_times(ll a, ll b){ ll w = 0; while(b){ if(b & 1) w = (w + a) % Mod; b >>= 1; a = (a + a) % Mod; } return w; }
[笔记] 快速乘
原文：https://www.cnblogs.com/LMSH7/p/9533383.html
