POJ 3232 Accelerator

二分

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>

#define LL long long int

using namespace std;

const int MAXN = 100010;

LL a[MAXN];
LL M, K;
int N;

bool check( LL mid )
{
    LL TotUse = mid * M;
    LL use = 0;
    for ( int i = 0; i < N; ++i )
    {
        if ( a[i] <= mid ) continue;
        if ( mid * K < a[i] ) return false;

        LL tp = ( a[i] - mid ) / ( K - 1 );
        if ( ( a[i] - mid ) % ( K - 1 ) ) ++tp;
        use += tp;
    }
    return use <= TotUse;
}

int main()
{
    int T;
   // freopen( "s.out", "w", stdout );
    scanf( "%d", &T );
    while ( T-- )
    {
        LL high = -1;
        scanf( "%d", &N );
        for ( int i = 0; i < N; ++i )
        {
            scanf( "%I64d", &a[i] );
            high = max( high, a[i] );
        }
        scanf( "%I64d%I64d", &M, &K );
        if ( K == 1 )
        {
            printf( "%I64d\n", high );
            continue;
        }

        LL l = 1, r = high;
        LL mid;
        while ( l < r )
        {
            mid = ( l + r ) >> 1;
            if ( check( mid ) )
            {
                r = mid;
            }
            else l = mid + 1;
        }
        printf( "%I64d\n", l );
    }
    return 0;
}