2021年CCCC-总决赛

目录

• 1-1
• 1-2
• 1-3
• 1-4
• 1-5
• 1-6
• 1-7
• 1-8
• 2-1
• 2-2
• 2-3
• 2-4
• 3-1
• 3-2

1-1

#include <bits/stdc++.h>

using namespace std;

int main() {
    cout << "To iterate is human, to recurse divine.";
    return 0;
}

1-2

#include <bits/stdc++.h>

using namespace std;

int n, m, k;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m >> k;
    cout << max(n - m * k, 0);
    return 0;
}

1-3

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

int n, m, k;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    string s;
    cin >> s;
    if (s.size() == 6) {
        cout << s.substr(0, 4) << '-' << s.substr(4, 2) << endl;
    } else {
        string x = s.substr(0, 2);
        if (x < "22") cout << "20";
        else cout << "19";
        cout << s.substr(0, 2) << '-' << s.substr(2, 2) << endl;
    }
    return 0;
}

1-4

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

int n, m, k;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    double a;
    cin >> n >> m;
    while (n--) {
        cin >> a;
        if (a < m) {
            cout << "On Sale! " << a << endl;
        }
    }
    return 0;
}

1-5

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

int n, m, k;
int a[50];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    for (int i = 0; i <= 23; ++i) {
        cin >> a[i];
    }
    while (cin >> m) {
        if (m < 0 || m > 23) break;
        cout << a[m];
        if (a[m] > 50) {
            cout << " Yes" << endl;
        } else {
            cout << " No" << endl;
        }
    }
    return 0;
}

1-6

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

int n, m, k;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    string s;
    cin >> n >> m;
    getline(cin, s);
    for (int i = 1; i <= n; ++i) {
        getline(cin, s);
        if (s.find("easy") != s.npos || s.find("qiandao") != s.npos) continue;
        if (!m) {
            cout << s << endl;
        }
        m--;
    }
    if (m >= 0) {
        cout << "Wo AK le" << endl;
    }
    return 0;
}

1-7

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

const int N = 2e4 + 7;
const int M = 1e6 + 7;

int n, m, k;
int a[N];
int num[M];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        num[ a[i] ]++; 
    }
    sort(a + 1, a + 1 + n);
    cout << a[1] << " " << num[ a[1] ] << endl;
    cout << a[n] << " " << num[ a[n] ] << endl;
    return 0;
}

1-8

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

const int N = 2e4 + 7;
const int M = 1e6 + 7;

int n, m, k;
int a[N];
int b[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    cin >> a[1] >> a[2] >> n;
    int i = 1;
    int tot = 2;
    while (tot <= n) {
        int tmp = a[i] * a[i + 1];
        int len = 0;
        do {
            b[len++] = tmp % 10;
            tmp /= 10;
        }while (tmp);
        while (len--) {
            a[++tot] = b[len];
        }
        i++;
    }
    for (int i = 1; i <= n; ++i) {
        cout << a[i] << " \n"[i == n];
    }
    return 0;
}

2-1

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

const int N = 2e4 + 7;
const int M = 1e6 + 7;

int n, m, k, op;
int a[N];
int b[N];
string s[N];
stack<char> sta;
int tot, last[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(1);
    cin >> n >> m >> k;
    for (int i = 1; i <= n; ++i) {
        cin >> s[i];
    }
    while (cin >> op, op != -1) {
        if (op == 0) {
            if (!sta.empty()) {
                cout << sta.top();
                sta.pop();
            }
            continue;
        }
        if (last[op] < m) {
            if (sta.size() == k) {
                cout << sta.top();
                sta.pop();
            }
            sta.push(s[op][last[op]++]);
        }
    }
    return 0;
}

2-2

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 1e4 + 7;

int n, m, k;
int in[N], head[N];
int path[N], ans[N];
int maxLen, tot;

void work(int len) {
    for (int i = 1; i <= len; ++i) {
        ans[i] = path[i];
    }
    maxLen = len;
}

bool cmp(int len) {
    for (int i = 1; i <= len; ++i) {
        if (ans[i] > path[i]) return true;
        if (ans[i] < path[i]) return false;
    }
    return false;
}

struct Edge {
    int nxt, v;
    
    Edge () {}
    Edge (int nxt, int v) : nxt(nxt), v(v) {}
}edge[N];

void addedge(int u, int v) {
    edge[tot] = Edge(head[u], v);
    head[u] = tot++;
}

void dfs(int u, int len) {
    path[len] = u;
    if (head[u] == -1) {
        if (len > maxLen) work(len);
        else if (len == maxLen && cmp(len)) work(len);
    }
    for (int i = head[u]; ~i; i = edge[i].nxt) {
        int v = edge[i].v;
        dfs(v, len + 1);
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> m;
        head[i] = -1;
        path[i] = -1;
        while (m--) {
            cin >> k;
            addedge(i, k);
            in[k]++;
        }
    }
    for (int i = 0; i < n; ++i) {
        if (!in[i]) {
            dfs(i, 1);
            break;
        }
    }
    cout << maxLen << endl;
    for (int i = 1; i <= maxLen; ++i) {
        cout << ans[i] << " \n"[i == maxLen];
    }
    return 0;
}

2-3

vector竟然能直接比大小，打个天梯赛学到许多Orz

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 1e4 + 7;

int n, m, k;
vector< vector<int> >v[N];
map< vector<int>, int >num;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m;
    
    for (int i = 0; i < n; ++i) {
        vector<int> G(m);
        for (int j = 0; j < m; ++j) {
            cin >> G[j];
        }
        num[G]++;
    }
    int ans = 0;
    for (auto t : num) {
        v[t.second].push_back(t.first);
        ans++;
    }
    cout << ans << endl;
    for (int i = n; i >= 1; --i) {
        for (auto t : v[i]) {
            cout << i;
            for (auto a : t) {
                cout << " " << a;
            }
            cout << endl;
        }
    }
    return 0;
}

2-4

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 1e5 + 7;

int n, m, k, op, id;
int sav[N];
vector<int> G[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1, t; i <= n; ++i) {
        cin >> k;
        while (k--) {
            cin >> t;
            G[i].push_back(t);
        }
    }
    int now = 1;
    while (m--) {
        cin >> op >> id;
        if (op == 0) {
            now = G[now][id - 1];
        }
        if (op == 1) {
            sav[id] = now;
            cout << now << endl;
        }
        if (op == 2) {
            now = sav[id];
        }
    }
    cout << now << endl;
    return 0;
}

3-1

发现求出距离之后每次答案都是能直接更新的。为了在所有点中找出最优的点，要用线段树维护一下。注意一下不能到的点。

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

typedef long long ll;

const int N = 1e5 + 7;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;

int n, m, q;
int head[2][N], tot[2];
ll dis[N], disR[N];
ll a[N];
ll money[N];

struct Edge {
    int nxt, v;
    ll w;
    
    Edge () {}
    Edge (int nxt, int v, ll w) : nxt(nxt), v(v), w(w) {}
}edge[2][N << 1];

struct qnode {
    int u;
    ll w;
    
    qnode () {}
    qnode (int u, ll w) : u(u), w(w) {}
    
    bool operator < (const qnode &a) const {
        return w > a.w;
    }
};

void addedge(int u, int v, ll w, int type) {
    edge[type][ tot[type] ] = Edge(head[type][u], v, w);
    head[type][u] = tot[type]++;
}

void Dijkstra(int s, int type, ll dis[]) {
    for (int i = 1; i <= n; ++i) {
        dis[i] = INF;
    }
    dis[s] = 0;
    priority_queue<qnode> q;
    q.push(qnode(s, 0));
    while (!q.empty()) {
        int u = q.top().u;
        q.pop();
        for (int i = head[type][u]; ~i; i = edge[type][i].nxt) {
            int v = edge[type][i].v;
            ll w = edge[type][i].w;
            if (dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                q.push(qnode(v, dis[v]));
            }
        }
    }
}

struct Seg {
    ll t[N << 2];
    
    void up(int id) {
        t[id] = min(t[id << 1], t[id << 1 | 1]);
    }
    
    void build(int id, int l, int r) {
        t[id] = 0;
        if (l == r) {
            t[id] = dis[l] + (disR[l] + money[l] - 1) / money[l];
            if (dis[l] == INF || disR[l] == INF) t[id] = INF;
            return;
        }
        int mid = l + r >> 1;
        build(id << 1, l, mid);
        build(id << 1 | 1, mid + 1, r);
        up(id);
    }
    
    void modify(int id, int l, int r, int pos, ll v) {
        if (l == r) {
            t[id] = dis[l] + (disR[l] + v - 1) / v;
            if (dis[l] == INF || disR[l] == INF) t[id] = INF;
            return;
        }
        int mid = l + r >> 1;
        if (pos <= mid) modify(id << 1, l, mid, pos, v);
        else modify(id << 1 | 1, mid + 1, r, pos, v);
        up(id);
    }
    
    ll query() {
        return t[1];
    }
}seg;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    memset(head, -1, sizeof(head));
    cin >> n >> m >> q;
    for (int i = 1, u, v, c, d; i <= m; ++i) {
        cin >> u >> v >> c >> d;
        addedge(u, v, c, 0);
        addedge(v, u, d, 1);
    }
    for (int i = 1; i <= n; ++i) {
        cin >> money[i];
    }
    Dijkstra(1, 0, dis);
    Dijkstra(n, 1, disR);
    seg.build(1, 1, n);
    for (int i = 1, x, y; i <= q; ++i) {
        cin >> x >> y;
        seg.modify(1, 1, n, x, y);
        cout << seg.query() << endl;	
    }
    return 0;
}

3-2

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

typedef long long ll;

const int N = 1e5 + 7;
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;

int n, m, k;
int p[N], ans[N];
vector<int> G[107], h[107];
bool vis[N];

bool check(int id, int pos) {
    for (auto v : h[id]) {
        if (v != p[pos]) return false;
        pos++;
    }
    return true;
}

bool dfs(int id, int now) {
    if (id >= n) return true;
    for (auto v : G[ p[id] ]) {
        if (vis[v]) continue;
        if (check(v, id)) {
            vis[v] = 1;
            ans[now] = v;
            if (dfs(id + h[v].size() - 1, now + 1)) return true;
            vis[v] = 0;
        }
    }
    return false;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> p[i];
    }
    cin >> m;
    for (int i = 1, t; i <= m; ++i) {
        cin >> k;
        for (int j = 1; j <= k; ++j) {
            cin >> t;
            h[i].push_back(t);
            if (j == 1) G[t].push_back(i);
        }
    }
    dfs(1, 1);
    for (int i = 1; i <= m; ++i) {
        cout << ans[i] << " \n"[i == m];
    }
    return 0;
}