Submission #666274

#	Time	Username	Problem	Language	Result	Execution time	Memory
666274		vuavisao	Pancake (NOI12_pancake)	C++14	25 / 25	67 ms	2540 KiB

pancake

#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define ll long long
using namespace std;

const int N = 8 + 1;

bool cakeee(int* val);
bool special_case_zero();
bool special_case_one();
bool special_case_two();
void bfs_make_cakeee();
void pre_process();
void solve();

int n;
int a[N];

int limit;
map<int, int> dist;

void bfs_make_cakeee() {
    auto get_hash = [&] (int* val) {
        int res = 0;
        for(int i = 1; i <= limit; ++ i) {
            res = res * 10 + val[i];
        }
        return res;
    };
    for(int cnt = 1; cnt <= 8; ++ cnt) {
        int tmp[N];
        limit = cnt;
        for(int j = 1; j <= limit; ++ j) tmp[j] = limit - j + 1;
        int st = get_hash(tmp);
        queue<int> q = {}; q.push(st);
        dist[st] = 0;
        while(q.empty() ^ 1) {
            int u = q.front(); q.pop();
            int tmp[N];
            int val = u;
            for(int i = limit; i >= 1; -- i) {
                tmp[i] = val % 10;
                val /= 10;
            }
            for(int i = 1; i <= limit; ++ i) {
                reverse(tmp + i, tmp + 1 + limit);
                int nxt = get_hash(tmp);
                reverse(tmp + i, tmp + 1 + limit);
                if(dist.find(nxt) != dist.end()) continue;
                dist[nxt] = dist[u] + 1;
//                cout << nxt << ' ' << dist[nxt] << ' ' << dist[u] << '\n';
                q.push(nxt);
            }
        }
    }
}

void solve() {
    cin >> n;
    for(int i = 1; i <= n; ++ i) cin >> a[i];
    a[0] = 1000000000;
    if(special_case_zero()) {
        cout << 0;
        return;
    }
    if(special_case_one()) {
        cout << 1;
        return;
    }
    if(special_case_two()) {
        cout << 2;
        return;
    }
//    assert(false);
    pre_process();
    auto get_hash = [&] (int* val) {
        int res = 0;
        for(int i = 1; i <= n; ++ i) {
            res = res * 10 + val[i];
        }
        return res;
    };
    cout << dist[get_hash(a)];
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen("Cake.inp", "r")) {
        freopen("Cake.inp", "r", stdin);
        freopen("Cake.out", "w", stdout);
    }
    bfs_make_cakeee();
    int t; cin >> t;
    while(t--) {
        solve();
        cout << '\n';
    }
    return 0;
}

bool special_case_zero() {
    return cakeee(a);
}

bool special_case_one() {
    int tmp[N];
    for(int i = 1; i <= n; ++ i) {
        for(int j = 0; j <= n; ++ j) tmp[j] = a[j];
        reverse(tmp + i, tmp + n + 1);
        if(cakeee(tmp)) return true;
    }
    return false;
}

bool special_case_two() {
    int tmp[N];
    for(int i = 1; i <= n; ++ i) {
        for(int j = 1; j <= n; ++ j) {
            for(int k = 0; k <= n; ++ k) tmp[k] = a[k];
            reverse(tmp + i, tmp + n + 1);
            reverse(tmp + j, tmp + n + 1);
            if(cakeee(tmp)) return true;
        }
    }
    return false;
}

bool cakeee(int* val) {
    for(int i = 1; i <= n; ++ i)
        if(val[i] > val[i - 1]) return false;
    return true;
}

void pre_process() {
    vector<int> Pos = {};
    for(int i = 1; i <= n; ++ i) {
        Pos.push_back(a[i]);
    }

    sort(Pos.begin(), Pos.end());
    Pos.resize(unique(Pos.begin(), Pos.end()) - Pos.begin());

    for(int i = 1; i <= n; ++ i) {
        a[i] = lower_bound(Pos.begin(), Pos.end(), a[i]) - Pos.begin() + 1;
    }
}

/// Code by vuavisao

Compilation message (stderr)

pancake.cpp: In function 'int32_t main()':
pancake.cpp:92:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |         freopen("Cake.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
pancake.cpp:93:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         freopen("Cake.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 8 / 8
• Subtask 5: 5 / 5