【bzoj1086】 scoi2005—王室联邦

http://www.lydsy.com/JudgeOnline/problem.php?id=1086 (题目链接)

题意

　　求将树分为几个联通块，每个联通块大小大于B小于3B，是否可行。

Solution

　　题都没看就翻了题解。。http://blog.csdn.net/popoqqq/article/details/42772237

代码

// bzoj3757
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#define MOD 1000000007
#define inf 2147483640
#define LL long long
#define free(a) freopen(a".in","r",stdin);freopen(a".out","w",stdout);
using namespace std;
inline LL getint() {
    LL x=0,f=1;char ch=getchar();
    while (ch>'9' || ch<'0') {if (ch=='-') f=-1;ch=getchar();}
    while (ch>='0' && ch<='9') {x=x*10+ch-'0';ch=getchar();}
    return x*f;
}

const int maxn=1010;
struct edge {int next,to;}e[maxn<<2];
int head[maxn],size[maxn],pos[maxn],q[maxn],n,B,cnt,top,c,cap[maxn];


void insert(int u,int v) {
    e[++cnt].to=v;e[cnt].next=head[u];head[u]=cnt;
    e[++cnt].to=u;e[cnt].next=head[v];head[v]=cnt;
}
void dfs(int x,int fa) {
    q[++top]=x;
    for (int i=head[x];i;i=e[i].next) if (e[i].to!=fa) {
            dfs(e[i].to,x);
            if (size[x]+size[e[i].to]>=B) {
                size[x]=0;
                cap[++cnt]=x;
                while (q[top]!=x) pos[q[top--]]=cnt;
            }
            else size[x]+=size[e[i].to];
        }
    size[x]++;
}
void paint(int x,int fa,int c) {
    if (pos[x]) c=pos[x];
    else pos[x]=c;
    for (int i=head[x];i;i=e[i].next) if (e[i].to!=fa) paint(e[i].to,x,c);
}
int main() {
    scanf("%d%d",&n,&B);
    for (int i=1;i<n;i++) {
        int u,v;
        scanf("%d%d",&u,&v);
        insert(u,v);
    }
    if (n<B) {printf("0");return 0;}
    cnt=0;dfs(1,0);
    if (!cnt) cap[++cnt]=1;
    paint(1,0,cnt);
    printf("%d
",cnt);
    for (int i=1;i<=n;i++) printf("%d ",pos[i]);
    printf("
");
    for (int i=1;i<=cnt;i++) printf("%d ",cap[i]);
    return 0;
}