C（C++也行）语言题（舞伴选择）求代码

#include #include #define rep(i,l,r) for (int i=l;i=l;--i)#ifdef WIN32#define LD "%I64d\n"#else#define LD "%lld\n"#endiftypedef long long LL;LL dfs(int l,int r){ if (l>=r) return 0; if (r-l==1) return (LL)l*r; int mid=(l+r)&