• You Are Given a Tree


    D. You Are Given a Tree
    time limit per test
    7 seconds
    memory limit per test
    512 megabytes
    input
    standard input
    output
    standard output

    A tree is an undirected graph with exactly one simple path between each pair of vertices. We call a set of simple paths kk-valid if each vertex of the tree belongs to no more than one of these paths (including endpoints) and each path consists of exactly kk vertices.

    You are given a tree with nn vertices. For each kk from 11 to nn inclusive find what is the maximum possible size of a kk-valid set of simple paths.

    Input

    The first line of the input contains a single integer nn (2n1000002≤n≤100000) — the number of vertices in the tree.

    Then following n1n−1 lines describe the tree, each of them contains two integers vv, uu (1v,un1≤v,u≤n) — endpoints of the corresponding edge.

    It is guaranteed, that the given graph is a tree.

    Output

    Output nn numbers, the ii-th of which is the maximum possible number of paths in an ii-valid set of paths.

    Examples
    input
    Copy
    7
    1 2
    2 3
    3 4
    4 5
    5 6
    6 7
    output
    Copy
    7
    3
    2
    1
    1
    1
    1

    input
    Copy
    6
    1 2
    2 3
    2 4
    1 5
    5 6
    output
    Copy
    6
    2
    2
    1
    1
    0

    Note

    One way to achieve the optimal number of paths for the second sample is illustrated in the following picture:

    #include <bits/stdc++.h>
    
    #define lowbit(x) x&(-x)
    using namespace std;
    typedef long long ll;
    const int maxn = 5e5 + 108;
    const ll mod = 1e9 + 7;
    int ooo = 800;
    
    struct node{
        int to,nx;
    }o[maxn];
    
    int n,tot,head[maxn],cal[maxn],res[maxn];
    int path;
    
    inline void add_edge(int u,int v){
        o[++tot].to=v;
        o[tot].nx=head[u];
        head[u]=tot;
    }
    
    inline void dfs(int cur,int fa,int chose){
        cal[cur]=0;
        bool flag=false;
        for(register int i=head[cur];i;i=o[i].nx){
            int to=o[i].to;
            if(to==fa)continue;
            dfs(to,cur,chose);
            if(cal[cur]+cal[to]>=chose-1)flag=true;
            cal[cur]=max(cal[cur],cal[to]);
        }
        if(flag||chose==1){
            ++path;
            cal[cur]=0;
        }
        else{
            ++cal[cur];
        }
    }
    
    inline void solve(int l,int r,int res_l,int res_r){
        if(l>r)return;
        if(res_l==res_r){
            for(register int i=l;i<=r;++i){
                res[i]=res_l;
            }
            return;
        }
        int mid=l+r>>1;
        path=0;
        dfs(1,0,mid);
        res[mid]=path;
        solve(l,mid-1,res[mid],res_r);
        solve(mid+1,r,res_l,res[mid]);
    }
    
    int main() {
    #ifndef ONLINE_JUDGE
        freopen("1.txt", "r", stdin);
    #endif
        scanf("%d",&n);
        for(register int i=1,u,v;i<n;++i){
            scanf("%d%d",&u,&v);
            add_edge(u,v);
            add_edge(v,u);
        }
        solve(1,n,0,n);
        for(register int i=1;i<=n;++i){
            printf("%d
    ",res[i]);
        }
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/czy-power/p/11474473.html
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