Codeforces Round #641 (Div. 2)

题目传送门

还是视频题解。
被卡D了，难受，D其实就逐个情况分析一下就能推出来了，但比赛的时候感觉没有一个明确的方向，导致思路很混乱。
为啥E过的人这么少？E感觉比D还简单，直接多源点BFS一下就行。

---

代码如下：

A. Orac and Factors

/*
 * Author:  heyuhhh
 * Created Time:  2020/5/12 20:36:40
 */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
  #define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
  void err() { std::cout << std::endl; }
  template<typename T, typename...Args>
  void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
  template <template<typename...> class T, typename t, typename... A> 
  void err(const T <t> &arg, const A&... args) {
  for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
  #define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
 
void run() {
    int n, k; cin >> n >> k;
    int t;
    for (int i = 2; i <= n; i++) {
        if (n % i == 0) {
           t = i; break;
        }
    }
    --k; n += t;
    n += 2 * k;
    cout << n << '
';
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cout << fixed << setprecision(20);
    int T; cin >> T; while(T--)
    run();
    return 0;
}

B. Orac and Models

/*
 * Author:  heyuhhh
 * Created Time:  2020/5/12 20:44:31
 */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
  #define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
  void err() { std::cout << std::endl; }
  template<typename T, typename...Args>
  void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
  template <template<typename...> class T, typename t, typename... A> 
  void err(const T <t> &arg, const A&... args) {
  for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
  #define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
 
int n;
int a[N];
 
vector <int> d[N];
 
void init() {
    for (int i = 1; i < N; i++) {
        for (int j = i + i; j < N; j += i) {
            d[j].emplace_back(i);
        }
    }   
}
 
void run() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    vector <int> f(n + 1, 1);
    for (int i = 2; i <= n; i++) {
        for (auto it : d[i]) {
            if (a[it] < a[i]) f[i] = max(f[i], f[it] + 1);
        }
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) ans = max(ans, f[i]);
    cout << ans << '
';
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cout << fixed << setprecision(20);
    init();
    int T; cin >> T; while (T--)
    run();
    return 0;
}

C. Orac and LCM

/*
 * Author:  heyuhhh
 * Created Time:  2020/5/12 20:51:42
 */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
  #define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
  void err() { std::cout << std::endl; }
  template<typename T, typename...Args>
  void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
  template <template<typename...> class T, typename t, typename... A> 
  void err(const T <t> &arg, const A&... args) {
  for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
  #define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5, M = 2e5 + 5;
 
int n;
int a[N];
vector <int> v[M];
 
ll qpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b & 1) res = res * a;
        a = a * a;
        b >>= 1;
    }
    return res;
}
 
void run() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    for (int i = 1; i <= n; i++) {
        int x = a[i];
        for (int j = 2; 1ll * j * j <= x; j++) {
            if (x % j == 0) {
                int cnt = 0;
                while (x % j == 0) {
                    x /= j;
                    ++cnt;
                }
                v[j].push_back(cnt);
            }
        }
        if (x > 1) {
            v[x].push_back(1);
        }
    }
    for (int i = 1; i < M; i++) {
        sort(all(v[i]));
    }
    ll ans = 1;
    for (int i = 1; i < M; i++) {
        if (sz(v[i]) <= n - 2) continue;
        if (sz(v[i]) == n - 1) {
            ans *= qpow(i, v[i][0]);
        } else {
            ans *= qpow(i, v[i][1]);
        }
    }
    cout << ans << '
';
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cout << fixed << setprecision(20);
    run();
    return 0;
}

D. Orac and Medians

/*
 * Author:  heyuhhh
 * Created Time:  2020/5/12 21:36:28
 */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
  #define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
  void err() { std::cout << std::endl; }
  template<typename T, typename...Args>
  void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
  template <template<typename...> class T, typename t, typename... A> 
  void err(const T <t> &arg, const A&... args) {
  for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
  #define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
 
int n;
int a[N];
 
void run() {
    int n, k; cin >> n >> k;
    int cnt = 0;
    for (int i = 1; i <= n; i++) {
        int x; cin >> x;
        if (x > k) a[i] = 1;
        else if (x < k) a[i] = -1;
        else a[i] = 0;
        if (a[i] == 0) ++cnt;
    }
    auto chk = [&] () {
        if (cnt == n) return true;
        if (cnt == 0) return false;
        for (int i = 1; i < n; i++) {
            if (a[i] >= 0 && a[i + 1] >= 0) return true;
        }
        for (int i = 1; i < n - 1; i++) {
            if (a[i] >= 0 && a[i + 2] >= 0) return true;       
        }
        return false;
    };
    if (chk()) cout << "yes" << '
';
    else cout << "no" << '
';
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cout << fixed << setprecision(20);
    int T; cin >> T; while(T--)
    run();
    return 0;
}

E. Orac and Game of Life

/*
 * Author:  heyuhhh
 * Created Time:  2020/5/12 23:56:30
 */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
  #define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
  void err() { std::cout << std::endl; }
  template<typename T, typename...Args>
  void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
  template <template<typename...> class T, typename t, typename... A> 
  void err(const T <t> &arg, const A&... args) {
  for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
  #define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e3 + 5;
const int dx[] = {-1, 1, 0, 0}, dy[] = {0, 0, -1, 1};
 
int n, m, t;
char s[N][N];
int a[N][N], dis[N][N];
bool vis[N][N];
 
void run() {
    cin >> n >> m >> t;
    for (int i = 1; i <= n; i++) {
        cin >> (s[i] + 1);
        for (int j = 1; j <= m; j++) {
            a[i][j] = (s[i][j] - '0');
        }
    }
    auto ok = [&] (int nx, int ny) {
        return nx >= 1 && nx <= n && ny >= 1 && ny <= m;
    };
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (!vis[i][j]) {
                for (int k = 0; k < 4; k++) {
                    int x = i + dx[k], y = j + dy[k];
                    if (ok(x, y) && a[x][y] == a[i][j]) {
                        vis[i][j] = true;
                    }
                }
            }
        }
    }
    memset(dis, INF, sizeof(dis));
    queue <pii> q;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (vis[i][j]) {
                q.push(MP(i, j));
                dis[i][j] = 0;
            }
        }
    }
    while (!q.empty()) {
        pii cur = q.front(); q.pop();
        int x = cur.fi, y = cur.se;
        auto ok = [&] (int nx, int ny) {
            return nx >= 1 && nx <= n && ny >= 1 && ny <= m && !vis[nx][ny] && dis[nx][ny] > dis[x][y] + 1;
        };
        for (int k = 0; k < 4; k++) {
            int nx = x + dx[k], ny = y + dy[k];
            if (ok(nx, ny)) {
                dis[nx][ny] = dis[x][y] + 1;
                vis[nx][ny] = true;
                q.push(MP(nx, ny));
            }
        }
    }
    while (t--) {
        int i, j; ll p;
        cin >> i >> j >> p;
        if (p <= dis[i][j] || dis[i][j] == INF) {
            cout << a[i][j] << '
';
        } else {
            int r = (p - dis[i][j]) % 2;
            cout << (a[i][j] ^ r) << '
';
        }
    }
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cout << fixed << setprecision(20);
    run();
    return 0;
}