oj.uz

Submission #1028134

# Submission time Handle Problem Language Result Execution time Memory
1028134 2024-07-19T14:17:21 Z anango Boarding Passes (BOI22_passes) C++17
0 / 100
 1 ms 604 KB 
#include <bits/stdc++.h>
#define int long long
using namespace std;
int INF = 1LL<<30;

void solve() {

    string S; cin >> S;
    int n = S.size();
    vector<int> ar(n); for (int i=0; i<n; i++) ar[i] = (S[i]-'A');
    int G = 15;
    int pref[n+1][G]; //count of character c, before index i
    int suff[n+1][G]; //count of character c, after or equal to index i
    for (int i=0; i<=n; i++) {
        for (int j=0; j<G; j++) {
            pref[i][j] = suff[i][j] = 0;
        }
    }
    for (int i=0; i<n; i++) {
        for (int j=0; j<=G; j++) {
            if (j==ar[i]) {
                pref[i+1][j] = pref[i][j]+1;
            }
            else {
                pref[i+1][j] = pref[i][j];
            }
        }
    }
    
    for (int i=n-1; i>=0; i--) {
        for (int j=0; j<G; j++) {
            if (j==ar[i]) {
                suff[i][j] = suff[i+1][j]+1;
            }
            else {
                suff[i][j] = suff[i+1][j];
            }
        }
    }
    //everyone before L boards from the front, everyone after or equal to it boards from the back. 
    vector<vector<int>> counts(G,vector<int>(G,0));     //counts[i][j] = sum of subsequences of (i,j) before l, and subsequences of (j,i) after L
    //counts[i][j] = sum of pref[k][j] for k<=L and ar[k]=i, and analogous expression for the suffix
    //first, get initial count values (for everyone boarding from the back)
    
    for (int j=0; j<G; j++) {
        for (int k=0; k<n; k++) {
            int i = ar[k];
            //cout << "adding " << i <<" " << j <<" " << k <<" " << j << " " << suff[k][j] << endl;
            counts[i][j] += suff[k+1][j];
        }
    }
    /*for (int i=0; i<G; i++) {
        for (int j=0; j<G; j++) {
            cout << i <<" " << j <<" " << counts[i][j] << endl;
        }
    }*/
    int ans = 1LL<<62;
    for (int L=0; L<n; L++) {


        vector<int> grps(G);
        for (int j=0; j<G; j++) grps[j] = j;
        sort(grps.begin(), grps.end(), [&](const int i1, const int i2) {
            return counts[i1][i2]>counts[i2][i1];
        });
        int su=0;
        for (int i=0; i<G; i++) {
            for (int j=0; j<i; j++) {
                su+=counts[grps[i]][grps[j]];
            }
        }
        int self = 0;
        for (int i=0; i<G; i++) {
            self+=counts[i][i];
        }
        //cout << L <<" " << su <<" " << self << " " << grps[0] <<" " << grps[1] <<" " << grps[2] << endl;
        ans=min(ans,su*2+self);

        //transfer L to the right
        int cur = ar[L];
        for (int j=0; j<G; j++) {
            int delta = suff[L+1][j];
            int delta2 = pref[L][j];
            counts[cur][j] -= delta-delta2;
        }
        
        /*cout << "TRANSFERRED TO " << L+1 << endl;
        for (int i=0; i<G; i++) {
            for (int j=0; j<G; j++) {
                cout << i <<" " << j <<" " << counts[i][j] << endl;
            }
        }
        cout << endl;*/
    }
    long double a2 = ans;
    a2/=2;
    cout << a2 << endl;
}

signed main() {
    int local=0;
    if (local) {
        // for getting input from input.txt
        freopen("input.txt", "r", stdin);
        // for writing output to output.txt
        freopen("output.txt", "w", stdout);
    }
    /*#ifdef ONLINE_JUDGE
    	ios_base::sync_with_stdio(false);
    	cin.tie(NULL);
    #endif*/ //fast IO
    solve();
    
}

Compilation message

passes.cpp: In function 'int main()':
passes.cpp:104:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         freopen("input.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
passes.cpp:106:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |         freopen("output.txt", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 604 KB 1st numbers differ - expected: '100800.5000000000', found: '100800.0000000000', error = '0.0000049603'
2 Halted 0 ms 0 KB -

Subtask #2
0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB found '1.0000000000', expected '1.0000000000', error '0.0000000000'
2 Correct 0 ms 384 KB found '1225.0000000000', expected '1225.0000000000', error '0.0000000000'
3 Incorrect 0 ms 344 KB 1st numbers differ - expected: '1023.0000000000', found: '1023.5000000000', error = '0.0004887586'
4 Halted 0 ms 0 KB -

Subtask #3
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB found '1.0000000000', expected '1.0000000000', error '0.0000000000'
2 Correct 0 ms 384 KB found '1225.0000000000', expected '1225.0000000000', error '0.0000000000'
3 Incorrect 0 ms 344 KB 1st numbers differ - expected: '1023.0000000000', found: '1023.5000000000', error = '0.0004887586'
4 Halted 0 ms 0 KB -

Subtask #4
0 / 40.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 604 KB 1st numbers differ - expected: '100800.5000000000', found: '100800.0000000000', error = '0.0000049603'
2 Halted 0 ms 0 KB -