BZOJ5281: [Usaco2018 Open]Talent Show 01分数规划+01背包

#include <bits/stdc++.h>

using namespace std ;

#define ll long long
#define N 1010
#define inf 0x3f3f3f3f

ll t[ N ] , w[ N ] , f[ N ] ;
int n , m ;

bool check( int x ) {
    for( int i = 1 ; i <= m ; i ++ ) f[ i ] = -inf ;
    for( int i = 1 ; i <= n ; i ++ ) {
        ll v = t[ i ] - w[ i ] * x ;
        for( int j = m ; j >= 0 ; j -- ) {
            if( f[ j ] == -inf ) continue ;
            int k = j + w[ i ] ;
            if( k > m ) k = m ;
            f[ k ] = max( f[ k ] , f[ j ] + v ) ;
        }
    }
    return f[ m ] >= 0 ;
}

int main() {
    scanf( "%d%d" , &n , &m ) ;
    for( int i = 1 ; i <= n ; i ++ ) {
        scanf( "%lld%lld" , &w[ i ] , &t[ i ] ) ;
        t[ i ] *= 1000 ;
    }
    int ans = 0 , l = 0 , r = 1e7 ;
    while( l <= r ) {
        int mid = ( l + r ) >> 1 ;
        if( check( mid ) ) l = mid + 1 , ans = mid ;
        else r = mid - 1 ;
    }
    printf( "%d\n" , ans ) ;
}