Submission #1122586

#	Time	Username	Problem	Language	Result	Execution time	Memory
1122586		LucaIlie	Let's Win the Election (JOI22_ho_t3)	C++20	100 / 100	2219 ms	4348 KiB

Main

#include <bits/stdc++.h>

using namespace std;

struct state {
    int a, b;
};

const int MAX_N = 500;
const double INF = 1e6;
int n, k;
state states[MAX_N + 1];
double dp[2][MAX_N + 1][MAX_N + 1];

double solve( int totalB ) {
    bool side = 0;
    for ( int a = 0; a <= k; a++ ) {
        for ( int b = 0; a + b <= k; b++ )
            dp[side][a][b] = INF;
    }
    dp[side][0][0] = 0.0;
    for ( int i = 1; i <= n; i++ ) {
        side ^= 1;
        for ( int a = 0; a <= k; a++ ) {
            for ( int b = 0; a + b <= k; b++ )
                dp[side][a][b] = dp[1 - side][a][b];
        }
        for ( int a = 0; a <= k - totalB; a++ ) {
            for ( int b = 0; a + b <= k && b <= totalB; b++ ) {
                dp[side][a + 1][b] = min( dp[side][a + 1][b], dp[1 - side][a][b] + (double)states[i].a / (totalB + 1));
                if ( states[i].b != -1 )
                    dp[side][a][b + 1] = min( dp[side][a][b + 1], dp[1 - side][a][b] + (double)states[i].b / (b + 1));
            }
        }
    }
    return dp[side][k - totalB][totalB];
}

int main() {

    cin >> n >> k;
    for ( int i = 1; i <= n; i++ )
        cin >> states[i].a >> states[i].b;
    cout << fixed << setprecision( 6 );

    sort( states + 1, states + 1 + n, []( state x, state y ) { return x.b < y.b; } );

    int l = 0, r = k + 1;
    while ( r - l > 1 ) {
        int mid = (l + r) / 2;

        if ( solve( mid ) < solve( mid - 1 ) )
            l = mid;
        else
            r = mid;
    }

    cout << solve( l ) << "\n";

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 11 / 11
• Subtask 4: 12 / 12
• Subtask 5: 33 / 33
• Subtask 6: 11 / 11
• Subtask 7: 23 / 23