1021. Deepest Root (25) PAT 甲级

来源：互联网发布：java中观察者模式编辑：程序博客网时间：2024/05/18 06:08
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#include<stdio.h>#include<set>#include<vector>using namespace std;#define MAX_N 10100set<int> temp,ans;vector<int> G[MAX_N];bool isRoot[MAX_N];int father[MAX_N];int n;int find(int x){    int r=x;    while(r!=father[r]){        r=father[r];    }    return r;}void merge(int a,int b){    int fa=find(a);    int fb=find(b);    if(fa!=fb){        father[fa]=fb;    }}void init(){    for(int i=1;i<=n;i++){        father[i]=i;    }}int findRoot(){    int count=0;    for(int i=1;i<=n;i++){        isRoot[find(i)]=true;    }    for(int i=1;i<=n;i++){        if(isRoot[i]){            count++;        }    }    //printf("count=%d\n",count);    return count;}int maxh=0;void dfs(int u,int height,int pre){    if(height>maxh){        temp.clear();        temp.insert(u);        maxh=height;    }    else if(height==maxh){        temp.insert(u);    }    for(int i=0;i<G[u].size();i++){        if(G[u][i]==pre)    continue;        else    dfs(G[u][i],height+1,u);    }}int main(){    scanf("%d",&n);    init();    int a,b;    for(int i=1;i<n;i++){        scanf("%d%d",&a,&b);        G[a].push_back(b);        G[b].push_back(a);        merge(a,b);    }    int flag=findRoot();    if(flag!=1){        printf("Error: %d components\n",flag);    }    else{        dfs(1,1,-1);        ans=temp;        dfs(*(ans.begin()),1,-1);        for(set<int>::iterator it=temp.begin();it!=temp.end();it++){            ans.insert(*it);        }        for(set<int>::iterator it=ans.begin();it!=ans.end();it++){            printf("%d\n",*it);        }    }}
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