learning follow 左程云老师 https://github.com/algorithmzuo/algorithm-journey改了下左老师计算小和的逻辑,Merge行为只用遍历一遍,代价是从只算加法变为需要乘法。 #include <bits/stdc++.h> using namespace std; using ll = long long; ll Merge(int* arr, int* temp, int l, int m, int r) { ll ans = 0, cur = l; int p1 = l, p2 = m + 1; ...