UVa 714 Copying Books

最大值最小化问题，二分+贪心，参考刘汝佳白皮书151页。

之前我的代码在UVa上交过了，但是在ZOJ上却是WA。

后来才发现是错在这两组数据：

2

4 3

100000 1 1 1

4 3

1 1 1 100000

#include <cstdio>
#include <cstring>

const int MAXN = 1000 + 10;

int m,k;
long long int num[MAXN];
long long int sum;
bool w[MAXN];

bool Judge( long long int x )
{
    int count = 0;
    long long int temp = 0;
    long long int temp2 = 0;
    for ( int i = 0; i < m; )
    {
        temp += num[i];
        if ( temp <= x ) i++;
        else
        {
            temp2 = temp;
            temp = 0;
            count++;
            if ( count > k ) return false;
        }
    }

    if ( temp2 != 0 ) count++;

    if ( count > k ) return false;
    else return true;
}

long long int Bsearch( long long int x, long long int y )
{
    long long int m;

    while ( x < y )
    {
        m = x + (y - x) / 2;
        if ( Judge(m) ) y = m;
        else x = m + 1;
    }
    return y;
}

void MaxSum( long long int x )
{
    long long int temp = 0;

    if ( m == k )
    {
        printf("%lld", num[0]);
        for ( int i = 1; i < m; i++ )
          printf(" / %lld", num[i]);
        putchar('\n');
        return;
    }

    if ( k == 1 )
    {
        printf("%lld", num[0]);
        for ( int i = 1; i < m; i++ )
          printf(" %lld", num[i]);
        putchar('\n');
        return;
    }

    int i = 0, j = 0;
    memset( w, false, sizeof(w) );

    for ( i = m - 1; i >= 0; )
    {
        temp += num[i];
        if ( temp <= x )
            i--;
        else
        {
            j++;
            w[i] = true;
            if ( k - j > i ) break;
            temp = 0;
        }
    }

    if ( j < k - 1 )
    {
        for ( int i = 0; i < m && j < k - 1; i++ )
            if ( !w[i] )
            {
                w[i] = true;
                j++;
            }
    }

    printf("%lld", num[0]);
    if ( w[0] )  printf(" /");
    for ( i = 1; i < m; i++ )
    {
        printf(" %lld", num[i]);
        if ( w[i] && i != m - 1 )  printf(" /");
    }

    putchar('\n');

    return;
}

int main()
{
    int T;
    scanf( "%d", &T );
    while ( T-- )
    {
        scanf("%d%d", &m, &k);
        sum = 0;
        for ( int i = 0; i < m; i++ )
        {
            scanf("%lld", &num[i]);
            sum += num[i];
        }

        MaxSum( Bsearch( 0, sum ) );
    }
    return 0;
}