Submission #579828

#	Time	Username	Problem	Language	Result	Execution time	Memory
579828		balbit	Boarding Passes (BOI22_passes)	C++14	100 / 100	310 ms	41268 KiB

passes

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define int ll
#define pii pair<ll, ll>
#define f first
#define s second

#define SZ(x) (int)(x).size()
#define ALL(x) (x).begin(), (x).end()
#define pb push_back

#define MX(a,b) a=max(a,b)
#define MN(a,b) a = min(a,b)
#define FOR(i,a,b) for (int i = a; i<b; ++i)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)

#ifdef BALBIT
#define bug(...) cerr<<"#"<<__LINE__<<": "<<#__VA_ARGS__<<"- ", _do(__VA_ARGS__)
template<typename T> void _do( T && x) {cerr<<x<<endl;}
template<typename T, typename ...S> void _do( T && x, S && ...y) {cerr<<x<<", "; _do(y...);}
#else
#define bug(...)
#define endl '\n'
#endif // BALBIT

const int maxn = 1e5+5;
int ps[15][maxn];
int a[maxn];

int frm[15][1<<15];
int sf[15][maxn], sb[15][maxn]; // sig front, sig back
vector<int> where[15];

const int G = 15;

ll dp[1<<15];

signed main(){
    ios::sync_with_stdio(0), cin.tie(0);

    bug(1,2);

    string _baa; cin>>_baa;
    int n = SZ(_baa);
    REP(i, n) {
        a[i+1] = _baa[i] - 'A';
    }
    // a is 1-indexed!!
    REP(g, G) {
        REP1(i,n) {
            ps[g][i] = ps[g][i-1] + (a[i] == g);
        }
    }

    REP1(i,n) {
        where[a[i]].pb(i);
    }

    REP(to,G) {

        memset(sf, 0, sizeof sf); memset(sb, 0, sizeof sb);

        REP(oth,G) {

            REP1(i,n) {
                sf[oth][i] = sf[oth][i-1];
                if (a[i] == to) {
                    sf[oth][i] += ps[oth][i-1];
                }
            }

            for (int i = n; i>=1; --i) {
                sb[oth][i] = sb[oth][i+1];
                if (a[i] == to) {
                    sb[oth][i] += (ps[oth][n] - ps[oth][i]);
                }
            }

        }


        REP(M, (1<<G)) {
            if (M & (1<<to)) continue;

            int bl = 0, br = SZ(where[to]); // first node where it's better to go to the right
            while (bl != br) {
                int bm = (bl + br) /2;
                int i = where[to][bm];
                int sl=ps[to][i-1],sr=(ps[to][n]-ps[to][i]);
                REP(oth, G) {
                    if (M & (1<<oth)) {
                        sl += ps[oth][i-1] * 2;
                        sr += (ps[oth][n] - ps[oth][i]) * 2;
                    }
                }
                if (sr < sl) {
                    br = bm;
                }else{
                    bl = bm+1;
                }
            }

            if (bl-1 >=0) {
                int i = where[to][bl-1];
                frm[to][M] += sf[to][i];
                REP(oth, G) {
                    if (M & (1<<oth)) {
                        frm[to][M] += sf[oth][i] * 2;
                    }
                }
            }
            if (bl < SZ(where[to])) {
                int i = where[to][bl];
                frm[to][M] += sb[to][i];
                REP(oth, G) {
                    if (M & (1<<oth)) {
                        frm[to][M] += sb[oth][i] * 2;
                    }
                }
            }
        }
    }

    memset(dp, 0x3f, sizeof dp);

    REP(M, (1<<G)) {
        if (M == 0) {
            dp[M] = 0; continue;
        }
        REP(j, G) {
            if (M & (1<<j)) {
                MN(dp[M], dp[M^(1<<j)] + frm[j][M^(1<<j)]);
            }
        }
    }
    ll re = dp[(1<<G)-1];
    if (re % 2 == 0) cout<<re/2<<endl;
    else cout<<(re/2)<<".5"<<endl;
//    cout<<(dp[(1<<G)-1]/2.0)<<endl;


}

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