bzoj 1086 树分块

将树分成一些块，做法见vfleaking博客。

/**************************************************************
    Problem: 1086
    User: idy002
    Language: C++
    Result: Accepted
    Time:20 ms
    Memory:852 kb
****************************************************************/
 
#include <cstdio>
#include <vector>
#define maxn 1010
using namespace std;
 
 
int n, b;
int mccno[maxn];
int cent[maxn], mtot;
vector<int> mcc[maxn];
vector<int> g[maxn], remain[maxn];
 
void dfs( int u, int fa ) {
    for( int t=0; t<g[u].size(); t++ ) {
        int v = g[u][t];
        if( v==fa ) continue;
        dfs(v,u);
        while( remain[v].size() ) {
            remain[u].push_back( remain[v].back() );
            remain[v].pop_back();
        }
        if( remain[u].size() >= b ) {
            mtot++;
            cent[mtot] = u;
            while( !remain[u].empty() ) {
                mccno[ remain[u].back() ] = mtot;
                mcc[ mtot ].push_back( remain[u].back() );
                remain[u].pop_back();
            }
        }
    }
    remain[u].push_back( u );
}
 
int main() {
    scanf( "%d%d", &n, &b );
    for( int i=1,u,v; i<n; i++ ) {
        scanf( "%d%d", &u, &v );
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(1,0);
    while( !remain[1].empty() ) {
        mccno[ remain[1].back() ] = mtot;
        mcc[ mtot ].push_back( remain[1].back() );
        remain[1].pop_back();
    }
    printf( "%d
", mtot );
    for( int i=1; i<=n; i++ )
        printf( "%d ", mccno[i] );
    printf( "
" );
    for( int i=1; i<=mtot; i++ )
        printf( "%d ", cent[i] );
    printf( "
" );
}