【LCA】 POJ 1470 Closest Common Ancestors

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给出一棵树再给出m个询问求m个询问后
最近每个点成为公共祖先的次数（输出大于0次的）
/** LCA离线算法，Tarjan*  复杂度O(n+Q);*/#include <cstdio>#include <cstring>#include <cstdlib>#include <string>#include <iostream>#include <algorithm>#include <sstream>#include <cmath>using namespace std;#include <queue>#include <stack>#include <vector>#include <deque>#define cler(arr, val)    memset(arr, val, sizeof(arr))#define FOR(i,a,b)  for(int i=a;i<=b;i++)#define IN   freopen ("in.txt" , "r" , stdin);#define OUT  freopen ("out.txt" , "w" , stdout);typedef long long  LL;const int MAXN = 1000+5;const int MAXM = 550000;const int INF = 0x3f3f3f3f;const int mod = 1000000007;int F[MAXN];//需要初始化为-1int find(int x){    if(F[x] == -1)return x;    return F[x] = find(F[x]);}void bing(int u,int v){    int t1 = find(u);    int t2 = find(v);    if(t1 != t2)        F[t1] = t2;}//************************bool vis[MAXN];//访问标记int ancestor[MAXN];//祖先struct Edge{    int to,next;} edge[MAXN*2];int head[MAXN],tot;void addedge (int u,int v){    edge[tot].to = v;    edge[tot].next = head[u];    head[u] = tot++;}struct Query{    int q,next;    int index;//查询编号} query[MAXM*2];int answer[MAXM];//存储最后的查询结果，下标0~Q-1int h[MAXM];int tt;int Q;void add_query(int u,int v,int index){    query[tt].q = v;    query[tt].next = h[u];    query[tt].index = index;    h[u] = tt++;    query[tt].q = u;    query[tt].next = h[v];    query[tt].index = index;    h[v] = tt++;}void init(){    tot = 0;    memset(head,-1,sizeof (head));    tt = 0;    memset(h,-1,sizeof(h));    memset(vis,false,sizeof(vis));    memset(F,-1,sizeof(F));    memset(ancestor,0,sizeof(ancestor));}void LCA(int u){    ancestor[u] = u;    vis[u] = true;    for(int i = head[u]; i != -1; i = edge[i].next)    {        int v = edge[i].to;        if(vis[v])continue;        LCA(v);        bing(u,v);        ancestor[find(u)] = u;    }    for(int i = h[u]; i != -1; i = query[i].next)    {        int v = query[i]. q;        if(vis[v])        {            answer[query[i].index] = ancestor[find(v)];        }    }}bool flag[MAXN];int Count_num[MAXN];int main(){#ifndef ONLINE_JUDGE    freopen("in.txt", "r", stdin);    // freopen("out.txt", "w", stdout);#endif    int k,u,v;    int n,m;    while(scanf("%d",&n)!=EOF)    {        init();        cler(flag,false);        for(int i=0; i<n; i++)        {            scanf("%d:(%d)",&u,&k);            for(int i=0; i<k; i++)            {                scanf("%d",&v);                flag[v]=true;                addedge(u,v);                addedge(v,u);            }        }        scanf("%d",&m);        for(int i=0; i<m; i++)        {            char s;            cin>>s;            scanf("%d %d)",&u,&v);            add_query(u,v,i);        }        int root;        for(int i=1; i<=n; i++)        {            if(!flag[i])            {                root=i;                break;            }        }        LCA(root);        cler(Count_num,0);        for(int i=0; i<m; i++)            Count_num[answer[i]]++;        for(int i=1; i<=n; i++)            if(Count_num[i]>0) printf("%d:%d\n",i,Count_num[i]);    }    return 0;}
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