1021. Deepest Root (25)

#include <iostream>
#include <queue>
#include <vector>
#include <string.h>using namespace std;int vis[10010], sum[10010], tree[10010], level;
queue<int> q;
vector<int> v[10010];void init(int n)
{int i;for(i = 1; i <= n; i++){tree[i] = -1;sum[i] = 1;}
}int findroot(int root)
{if(tree[root] == -1){return root;}else{tree[root] = findroot(tree[root]);return tree[root];}
}void buildrelation(int index[2])
{int i;for(i = 0; i <= 1; i++){index[i] = findroot(index[i]);}int index0 = index[0], index1 = index[1];if(index0 != index1){if(sum[index1] > sum[index0]){index0 = index[1];index1 = index[0];}tree[index1] = index0;sum[index0] += sum[index1];}
}void bfs()
{int qsize = q.size(), vsize, cur, i, next;level++;while(qsize--){cur = q.front();q.pop();vsize = v[cur].size();for(i = 0; i <= vsize - 1; i++){next = v[cur][i];if(vis[next] == 0){vis[next] = 1;q.push(next);}}}qsize = q.size();if(qsize > 0){bfs();}
}int getrootcount(int n)
{int i, count = 0;for(i = 1; i <= n; i++){if(tree[i] == -1){count++;}}return count;
}int main()
{int n;scanf("%d", &n);init(n);int i, a, b, index[2];for(i = 1; i <= n - 1; i++){scanf("%d%d", &a, &b);v[a].push_back(b);v[b].push_back(a);index[0] = a;index[1] = b;buildrelation(index);}int count = getrootcount(n);if(count > 1){printf("Error: %d components\n", count);return 0;}int max = 0;vector<int> res;for(i = 1; i <= n; i++){memset(vis, 0, sizeof(vis));vis[i] = 1;level = 0;q.push(i);bfs();if(level > max){max = level;res.clear();res.push_back(i);}else if(level == max){res.push_back(i);}}int size = res.size();for(i = 0; i <= size - 1; i++){printf("%d\n", res[i]);}system("pause");return 0;
}