Submission #997749

#	Time	Username	Problem	Language	Result	Execution time	Memory
997749		yeediot	Portal (BOI24_portal)	C++17	100 / 100	17 ms	3420 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}
#ifdef local
void CHECK();
void setio(){
    freopen("/Users/iantsai/cpp/input.txt","r",stdin);
    freopen("/Users/iantsai/cpp/output.txt","w",stdout);
}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
#define TOI_is_so_de ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);setio();
tuple<int,int,int>exgcd(int a, int b){
    if(b == 0)return {a, 1, 0};
    int q=a/b;
    auto [g, s, t] = exgcd(b, a-q*b);
    return {g, t, s-q*t};
}
signed main(){
    TOI_is_so_de;
    int n;
    cin >> n;
    vector<pii>p(n+1);
    int d[2][n];
    memset(d, 0 ,sizeof(d));
    for(int i=0;i<n;i++){
        cin >> p[i].F >> p[i].S;
    }
    for(int i=0;i+1<n;i++){
        d[0][i] = p[i+1].F-p[i].F;
        d[1][i] = p[i+1].S-p[i].S;
    }
    for(int i=0;i+1<n;i++){
        if(d[0][i]){
            swap(d[0][i], d[0][0]);
            swap(d[1][i], d[1][0]);
            break;
        }
    }
    if(d[0][0] == 0){
        cout << -1 << '\n';
        return 0;
    }
    int ans = 0;
    for(int i=1;i+1<n;i++){
        auto [g, s, t] = exgcd(d[0][0], d[0][i]);
        int f = d[0][0]*s+d[0][i]*t;
        int f2 = d[1][0]*s+d[1][i]*t;
        //可以想成把兩個向量的x座標都變成最小公倍數
        //只能是最小公倍數不能直接是兩者積的原因是這樣不會是最小循環
        //不能先把d[0]向量變(g,val)，之後d[i]向量減掉d[0]向量的某個倍數使他變(0,s)是因為
        //exgcd有可能找到的解是(0,1)，這樣減完會變0向量不合。
        s = (d[1][0]*-d[0][i]+d[1][i]*d[0][0])/g;
        d[0][0] = f, d[1][0] = f2;
        if(ans) d[1][0] %= ans;
        ans = gcd(ans, s);
    }
    ans = abs(ans*d[0][0]);
    cout << (ans == 0 ? -1 : ans) << '\n';
    #ifdef local
    CHECK();
    #endif
}
/*
input:
 2 -1
 0  2
*/
#ifdef local
void CHECK(){
    cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
     function<bool(string,string)> compareFiles = [](string p1, string p2)->bool {
         std::ifstream file1(p1);
         std::ifstream file2(p2);
         if (!file1.is_open() || !file2.is_open())return false;
         std::string line1, line2;
         while (getline(file1, line1) && getline(file2, line2)) {
             if (line1 != line2)return false;
         }
         int cnta=0,cntb=0;
         while(getline(file1,line1))cnta++;
         while(getline(file2,line2))cntb++;
         return cntb-cnta<=1;
     };
     bool check = compareFiles("output.txt","expected.txt");
     if (check) cerr<<"ACCEPTED\n";
     else cerr<<"WRONG ANSWER!\n";
}
#else
#endif



 

Compilation message (stderr)

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:35:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:36:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 29 / 29
• Subtask 5: 15 / 15
• Subtask 6: 35 / 35