去年暑假打过一次，但是当时太菜，今天看到之前写过，好奇多少分，考后交了一发，发现自己是真的菜
然后，就算开了个坑吧，四道题。。。
A. 数列
\(exgcd\)板子
然后，\(exgcd\)咋用来着？
滚回去学数论基础了
code
#include <cstdio>
using namespace std;
#define int long long
int min(int x, int y) { return x < y ? x : y; }
int max(int x, int y){return x > y ? x : y;}
int abs(int x) { return x < 0 ? -x : x; }
void swap(int &x, int &y){x ^= y; y ^= x; x ^= y;}
int exgcd(int a, int b, int &x, int &y){
if(b == 0){
x = 1; y = 0;
return a;
}
int gcd = exgcd(b, a % b, y, x);
y = y - a / b * x;
return gcd;
}
signed main(){
int n, a, b;
scanf("%lld%lld%lld", &n, &a, &b);
int x, y; if(a > b)swap(a, b);
int gcd = exgcd(a, b, x, y);
b = b / gcd; a = a / gcd;
x = (x % b + b) % b;
int ans = 0;
bool flag = 1;
for (int i = 1; i <= n; ++i){
int now; scanf("%lld",&now); now = abs(now);
if(now % gcd)flag = 0;
if(flag){
now = now / gcd;
int nx = (x * now % b + b) % b;
int ny = (now - a * nx) / b;
ans += min(abs(nx) + abs(ny), abs(nx - b) + abs(ny + a));
}
}
if(flag)printf("%lld\n", ans);
else printf("-1\n");
return 0;
}