Submission #387656

#	Time	Username	Problem	Language	Result	Execution time	Memory
387656		2qbingxuan	Cheerleaders (info1cup20_cheerleaders)	C++14	100 / 100	449 ms	3900 KiB

cheerleaders

#include <bits/stdc++.h>
#ifdef local
#define debug(a...) qqbx(#a, a)
template <typename ...T> void qqbx(const char *s, T ...a) {
    int cnt = sizeof...(T);
    ((std::cerr << "\033[1;32m(" << s << ") = (") , ... , (std::cerr << a << (--cnt ? ", " : ")\033[0m\n")));
}
#define pary(a...) danb(#a, a)
template <typename T> void danb(const char *s, T L, T R) {
    std::cerr << "\033[1;32m[ " << s << " ] = [ ";
    for (int f = 0; L != R; ++L) std::cerr << (f++ ? " " : "") << *L;
    std::cerr << " ]\033[0m\n";
}
#else
#define debug(...) ((void)0)
#define pary(...) ((void)0)
#endif // local
#define all(v) begin(v),end(v)
#define pb emplace_back

using namespace std;
using ll = int64_t;
const int inf = 1e9, MOD = 1000000007, maxn = 1 << 18, maxLg = 18;

struct Trie {
    int ch[maxn][2], cnt[maxn], tot;
    ll tag[maxLg][2];
    int n;
    void insert(int x) {
        int now = 0;
        for (int i = n-1; i >= 0; i--) {
            int d = x >> i & 1;
            if (!ch[now][d])
                ch[now][d] = ++tot;
            if (ch[now][!d])
                tag[i][!d] += cnt[ch[now][!d]];
            now = ch[now][d];
            ++cnt[now];
        }
    }
    pair<ll,int> getBest() {
        ll ans = 0;
        int x = 0;
        for (int i = 0; i < n; i++) {
            if (tag[i][0] < tag[i][1])
                ans += tag[i][0];
            else
                ans += tag[i][1], x ^= 1<<i;
        }
        return { ans, x };
    }
    void init() {
        memset(ch, 0, sizeof ch);
        memset(cnt, 0, sizeof cnt);
        memset(tag, 0, sizeof tag);
        tot = 0;
    }
} trie;
int pos[maxn];
pair<ll,int> calc(int n) {
    trie.init();
    for (int i = 0; i < (1<<n); i++)
        trie.insert(pos[i]);
    pary(pos, pos+(1<<n));
    return trie.getBest();
}
signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n;
    cin >> n;
    trie.n = n;
    for (int i = 0, x; i < (1<<n); i++) {
        cin >> x;
        pos[x] = i;
    }
    if (n == 0)
        return cout << 0 << '\n', 0;
    ll ans = 1e18;
    int bestShift = 0;
    int bestX = 0;
    for (int shift = 0; shift < n; shift++) {
        auto [cost, x] = calc(n);
        if (ans > cost) {
            ans = cost;
            bestShift = shift;
            bestX = x;
        }
        for (int i = 0; i < (1<<n); i++)
            pos[i] = (pos[i] >> 1) | ((pos[i] & 1) << (n-1));
    }
    cout << ans << '\n';

    debug(bestX);
    string op;
    for (int i = 0; i < bestShift; i++)
        op += '2';
    for (int i = 0; i < n; i++) {
        op += '2';
        if (~bestX >> i & 1)
            op += '1';
    }
    cout << op << '\n';
}

Compilation message (stderr)

cheerleaders.cpp: In function 'int main()':
cheerleaders.cpp:82:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   82 |         auto [cost, x] = calc(n);
      |              ^

• Subtask 1: 16 / 16
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 21 / 21
• Subtask 5: 28 / 28