关于 freopen In NOIP

#define ffopen(s) \
cin.tie(0)->sync_with_stdio(0), cout.tie(0), cerr.tie(0); \
if (*#s) freopen(#s ".in", "r", stdin); \
if (*#s) freopen(#s ".out", "w", stdout); \
//
#include <bits/stdc++.h>
#define chkmax(x, y) ((x)=max((x),(y)))
#define chkmin(x, y) ((x)=min((x),(y)))
using namespace std;
int main() { ffopen(edit); // 比如这题代码为 edit.cpp
  return 0;
}