Submission #589326

#	Time	Username	Problem	Language	Result	Execution time	Memory
589326		maomao90	Boarding Passes (BOI22_passes)	C++17	5 / 100	2 ms	1748 KiB

passes

// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;
 
#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;
 
#ifndef DEBUG
#define cerr if (0) cerr
#endif
 
const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;
const int MAXN = 100005;
const int MAXG = 15;
 
int n, g;
string s;
int psm[MAXG][MAXN];
ll pre[MAXG + 5][MAXG + 5][MAXN];
ll dp[(1 << MAXG) + 5];
 
inline ll calc(int n) {
    return (ll) n * (n - 1) / 2;
}
 
int main() {
    #ifndef DEBUG
    ios::sync_with_stdio(0), cin.tie(0);
    #endif
    cin >> s;
    n = SZ(s);
    REP (i, 0, n) {
        mxto(g, s[i] - 'A' + 1);
    }
    REP (i, 0, g) {
        REP (j, 0, n) {
            if (s[j] - 'A' == i) {
                psm[i][j] = 1;
            }
            if (j) {
                psm[i][j] += psm[i][j - 1];
            }
        }
    }
    REP (j, 0, g) {
        REP (i, 0, g) {
            int all = 0;
            REP (k, 0, n) {
                if (s[k] - 'A' == i) {
                    all++;
                }
            }
            int acnt = 0, ajc = 0;
            ll cur = 0;
            RREP (k, n - 1, 0) {
                if (s[k] - 'A' == j) {
                    cur += acnt * 2;
                    ajc++;
                } else if (s[k] - 'A' == i) {
                    acnt++;
                }
            }
            int jc = 0, cnt = 0;
            REP (k, 0, n) {
                if (s[k] - 'A' == j) {
                    cur += cnt * 2;
                    cur -= acnt * 2;
                    jc++;
                } else if (s[k] - 'A' == i) {
                    cnt++;
                    acnt--;
                }
                pre[j][i][k] = cur;
            }
        }
    }
    dp[0] = 0;
    REP (i, 1, 1 << g) {
        dp[i] = LINF;
        // cerr << bitset<2>(i) << '\n';
        REP (j, 0, g) {
            if (i >> j & 1 ^ 1) {
                continue;
            }
            // cerr << ' ' << j << '\n';
            int ni = i ^ (1 << j);
            ll mn = LINF;
            auto solve = [&] (int k) {
                ll tmp = calc(psm[j][k]) + calc(psm[j][n - 1] - psm[j][k]);
                REP (l, 0, g) {
                    if (i >> l & 1 ^ 1) {
                        continue;
                    }
                    tmp += pre[j][l][k];
                }
                return tmp;
            };
            mnto(dp[i], dp[ni] + solve(0));
            int lo = 0, hi = n - 1;
            // REP (i, 0, n) {
            //     cerr << "   " << i << ": " << solve(i) << '\n';
            // }
            while (hi - lo >= 3) {
                int mid1 = lo + (hi - lo + 1) / 3, mid2 = mid1 + hi >> 1;
                assert(mid1 != mid2);
                // cerr << "  " << lo << ' ' << hi << ' ' << mid1 << ' ' << mid2 << '\n';
                ll tmp1 = solve(mid1), tmp2 = solve(mid2);
                if (tmp1 <= tmp2) {
                    hi = mid2;
                } else {
                    lo = mid1;
                }
            }
            REP (k, lo, hi + 1) {
                mnto(dp[i], dp[ni] + solve(k));
            }
        }
    }
    ll ans = dp[(1 << g) - 1];
    if (ans % 2 == 0) {
        ans /= 2;
        cout << ans << '\n';
    } else {
        ans /= 2;
        cout << ans << ".5\n";
    }
    return 0;
}

Compilation message (stderr)

passes.cpp: In function 'int main()':
passes.cpp:104:24: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
  104 |             if (i >> j & 1 ^ 1) {
      |                 ~~~~~~~^~~
passes.cpp: In lambda function:
passes.cpp:113:32: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
  113 |                     if (i >> l & 1 ^ 1) {
      |                         ~~~~~~~^~~
passes.cpp: In function 'int main()':
passes.cpp:126:64: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  126 |                 int mid1 = lo + (hi - lo + 1) / 3, mid2 = mid1 + hi >> 1;
      |                                                           ~~~~~^~~~
passes.cpp:109:16: warning: unused variable 'mn' [-Wunused-variable]
  109 |             ll mn = LINF;
      |                ^~

• Subtask 1: 5 / 5
• Subtask 2: 0 / 25
• Subtask 3: 0 / 30
• Subtask 4: 0 / 40