HDU 4671 Backup Plan 构造

负载是否平衡只与前两列有关，剩下的只要与前两列不重复就随便放。

第一列我们按1-n这样循环放，第二列每次找个数最少的那个服务器放。

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

using namespace std;

const int MAXN = 110;

int N, M;
int mat[MAXN][MAXN];
int cnt[MAXN];
int ori[MAXN];
bool vis[MAXN];

void show()
{
    for ( int i = 1; i <= M; ++i )
    {
        for ( int j = 1; j <= N; ++j )
        {
            if ( j != 1 ) putchar(' ');
            printf( "%d", mat[i][j] );
        }
        puts("");
    }
    //puts("=========");
    return;
}

void FangHang( int *a )
{
    memset( vis, false, sizeof(vis) );
    vis[ a[1] ] = true;
    vis[ a[2] ] = true;

    for ( int i = 3; i <= N; ++i )
    {
        for ( int j = 1; j <= N; ++j )
        if ( !vis[j] )
        {
            a[i] = j;
            vis[j] = true;
            break;
        }
    }

    return;
}

int GetMin( int now )
{
    int minn = 1 << 30;
    int ansi;
    for ( int i = 1; i <= N; ++i )
    {
        if ( i == now ) continue;
        if ( cnt[i] < minn )
        {
            minn = cnt[i];
            ansi = i;
        }
    }
    return ansi;
}

void solved()
{
    memset( cnt, 0, sizeof(cnt) );
    for ( int i = 1; i <= M; ++i )
        ++cnt[ mat[i][1] ];

    int fang = 0;
    int cur = 1;
    for ( int i = 1; i <= N; ++i ) ori[i] = cnt[i];
    while ( fang < M )
    {
        int minn;
        int j = 1;
        while ( j <= M )
        {
            minn = GetMin(cur);
            for ( ; j <= M; ++j )
            {
                if ( mat[j][1] == cur && mat[j][2] == -1 )
                {
                    mat[j][2] = minn;
                    ++cnt[ minn ];
                    ++fang;
                    break;
                }
            }
        }
        for ( int i = 1; i <= N; ++i ) cnt[i] = ori[i];
        ++cur;
    }

    for ( int i = 1; i <= M; ++i )
    {
        FangHang( mat[i] );
    }

    return;
}

int main()
{
    while ( scanf( "%d%d", &N, &M ) == 2 )
    {
        memset( mat, -1, sizeof(mat) );
        int i = 1, j = 1;
        while ( i <= M )
        {
            mat[i][1] = j;
            ++i, ++j;
            if ( j > N ) j = 1;
        }
        solved();
        show();
    }
    return 0;
}