POJ 3107 Godfather

静态链表。。STL要超时。。

#include <iostream>
#include <cstdio>
#include <vector>
#include <cstring>
using namespace std;

vector<int> G[50001];
int dp[50001],visit[50001],head[50001];
int n,k;
struct Edge
{
    int v;
    int next;
}edge[50001 * 2];
int max(int a,int b)
{
    return a > b ? a : b;
}

int min(int a,int b)
{
    return a < b ? a : b;
}

void addedge(int a,int b)
{
    edge[k].v = b;
    edge[k].next = head[a];
    head[a] = k;
    k++;
}
int dfs(int u)
{
    visit[u] = true;
    int sum = 1,temp;
    for(int i = head[u];i;i = edge[i].next)
    {
        int v = edge[i].v;
        if(visit[v])
            continue;
        temp = dfs(v);
        sum += temp;
        dp[u] = max(dp[u],temp);
    }
    dp[u] = max(dp[u],n - sum);
    return sum;
}

int main()
{
    scanf("%d",&n);
    int a,b;
    memset(visit,false,sizeof(visit));
    memset(dp,0,sizeof(dp));
    memset(head,0,sizeof(head));
    k = 1;
    for(int i = 1;i <= n - 1;i++)
    {
        scanf("%d%d",&a,&b);
        addedge(a,b);
        addedge(b,a);
    }
    dfs(1);
    int ans = 0xffffff;
    for(int i = 1;i <= n;i++)
    {
        ans = min(ans,dp[i]);
    }
    bool flag = true;
    for(int i = 1;i <= n;i++)
    {
        if(dp[i] == ans)
        {
            if(flag)
            {
                printf("%d",i);
                flag = false;
            }
            else
            {
                printf(" %d",i);
            }
        }
    }
    printf("\n");
    return 0;
}