// poj3107 Godfather
#include <cstdio>
#include <cstring>
#define NDEBUG#define MAXN    50005using namespace std;int N;
int edgefw[MAXN*2], edge[MAXN*2], head[MAXN], eptr;#define EI(j, k)    ({ \edge[eptr] = k, edgefw[eptr] = head[j];    \head[j] = eptr++;    \
})int dp[MAXN], dp2[MAXN];
char vis[MAXN];void dfs(int i)
{vis[i] = 1;int p, maxk = 0, sumn = 1;for(p = head[i]; p>=0; p = edgefw[p]) {int t = edge[p];if (!vis[t]) {if (!dp2[t]) dfs(t);sumn += dp2[t];if (maxk < dp2[t])maxk = dp2[t];}}if (sumn != N && N - sumn > maxk) maxk = N - sumn;dp[i] = maxk, dp2[i] = sumn;
}int main(void)
{#ifndef NDEBUGfreopen("poj3107.in", "r", stdin);#endif // NDEBUGscanf("%d", &N);memset(head, -1, sizeof(int) * N), eptr = 0;int i, j, root;root = 0;for(i=1; i<N; ++i) {int k;scanf("%d%d", &j, &k);--j,--k; EI(j, k), EI(k, j);if (root == k) root = j;}dfs(root);j = 0;for(i = 1; i < N; ++i)if (dp[i] < dp[j])j = i;root = 0;for(i = 0; i < N; ++i)if (dp[i] == dp[j]) {printf("%d", ++i);break;}for(; i<N; ++i)if (dp[i] == dp[j])printf(" %d", i+1);putchar('\n');return 0;
}

 1 #include <cstdio>
 2 #include <cstring>
 3 using namespace std;
 4
 5
 6 #define FOR(p,i,s,t) for(__typeof(p) i=s; i<t; ++i)
 7 #define REP(t,i,n)    FOR(t,i,0,n)
 8
 9 #define ECH(it, A) for (__typeof(A.begin()) it=A.begin(); it != A.end(); ++it)
10 #define RST(x,y) memset(x, y, sizeof(x))
11 #define RST0(x)    RST(x,0)
12
13 typedef int Vt, Lt;
14 const __typeof(Vt) MAXV = 50005;
15
16 #define MAXE    ((MAXV<<1) - 2)
17
18 Vt Vefw[MAXE], Veh[MAXV], eptr = 0;
19 struct Vedge {
20     Vt t;
21     Lt l;
22     Vedge() {}
23     Vedge(Vt _t): t(_t), l(1) {}
24     Vedge(Vt _t, Lt _l): t(_t), l(_l) {}
25     void attach(Vt s) {
26         extern Vedge Vs[];
27         memcpy(Vs + eptr, this, sizeof(Vedge));
28         Vefw[eptr] = Veh[s]; Veh[s] = ++eptr;
29     }
30 };
31 #define addedge(s,t,l) ({Vedge e(t,l); e.attach(s);})
32 Vedge Vs[MAXE];
33 Vt gcoref_tot;
34 char gc_8[MAXV];
35 Vt gc_maxk[MAXV], gc_sumn[MAXV];
36
37 int gc_root;
38
39 void gcoref(Vt i)
40 {
41     char _gc8;
42     if (!(_gc8 = gc_8[i])) gc_8[i] = -1;    // 遍历去环
43     Vt sumn = 1, maxk = 0;
44     for(Vt e = Veh[i]; e; e = Vefw[e]) {
45         Vt t = Vs[--e].t;
46         if (!gc_8[t]) {
47             gcoref(t);
48             sumn += gc_sumn[t];
49             if (maxk < gc_sumn[t])
50                 maxk = gc_sumn[t];
51         }
52     }
53     gc_8[i] = _gc8;                // gc_8还有其他用途
54     if (gcoref_tot - sumn > maxk) maxk = gcoref_tot - sumn;
55     gc_sumn[i] = sumn, gc_maxk[i] = maxk;
56     if (gc_maxk[gc_root] > maxk) gc_root = i;
57 }
58
59 inline Vt gcore(Vt root)
60 {
61     gc_maxk[gc_root = root] = gcoref_tot;
62     gcoref(root);
63     return gc_root;
64 }
65
66 int N;
67
68 // 本模板使用方式：  gcoref_tot = 实际节点数
69 // gc_8 != 0, 该节点被剪掉（忽略），可以用来存储其他信息
70 // addedge加边（注意针对 无根树 要加双向），gcore返回重心节点
71 // gc_maxk里面存储所有节点的最大真子树的节点数.
72
73 int main(void)
74 {
75 //    freopen("poj3107.txt", "r", stdin);
76     scanf("%d", &N);
77     Vt root = 0;
78     REP(int, i, N-1) {
79         Lt l;
80         Vt s,t;
81         scanf("%d%d", &s, &t); --s, --t;
82         addedge(s,t,1), addedge(t,s,1);
83         if (root == t) root = s;
84     }
85     gcoref_tot = N;
86     root = gcore(root);
87     Vt i;
88     for(i = 0; i < N; ++i)
89         if (gc_maxk[i] == gc_maxk[root]) {
90             printf("%d", ++i);
91             break;
92         }
93     for(; i<N; ++i)
94         if (gc_maxk[i] == gc_maxk[root])
95             printf(" %d", i+1);
96     putchar('\n');
97     return 0;
98 }