HDU 4409 - Family Name List(模拟树+lca)

来源：互联网发布：网络种地实例编辑：程序博客网时间：2024/06/05 18:57
题目：
http://acm.hdu.edu.cn/showproblem.php?pid=4409
思路：
模拟输出树，暴力求解LCA
AC.
#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>#include <cmath>#include <set>#include <map>using namespace std;const int maxn = 30005;char s[70],ch[70];int pre[maxn],son[maxn],dep[maxn];char now[maxn][70];char name[maxn][70];map<string,int> idx;set<string> st;struct Edge{    int to,next;}edge[maxn];int head[maxn],tot,cnt;void init(){    memset(head,-1,sizeof(head));    tot = 0;}void add(int u,int v){    edge[tot].to = v;    edge[tot].next = head[u];    head[u] = tot++;}set<string>::iterator ite;void dfs(int u){    st.clear();    int dfsci[maxn];    int num = 0;    for(int i = head[u]; i != -1; i = edge[i].next)    {        int v = edge[i].to;        st.insert(name[v]);    }    for(ite = st.begin(); ite != st.end(); ite++)       dfsci[num++] = idx[*ite];    for(int i = 0; i < num; i++)    {        int v = dfsci[i];        for(int j = 0; j < dep[v]; j++)            now[cnt][j] = '.';        now[cnt][dep[v]] = 0;        strcat(now[cnt],name[v]);        cnt++;        dfs(v);    }}int main(){    //freopen("in","r",stdin);    int n;    while(scanf("%d",&n) && n)    {        memset(pre,-1,sizeof(pre));        memset(son,0,sizeof(son));        idx.clear();        init();        for(int i = 1; i <= n; i++)        {            scanf("%s",s);            int len = strlen(s);            int step = 0, j;            for(j = 0; j < len; j++)                if(s[j] == '.') step++;                else break;            strncpy(ch,&s[j],len-step);            ch[len - step] = 0;            dep[i] = step;            if(step == 0)                pre[i] = 0,son[0] = 1;            else            {                int tmp = idx[now[step-1]];                pre[i] = tmp;                son[tmp]++;                add(tmp,i);            }            strcpy(now[step],ch);            idx[ch] = i;            strcpy(name[i],ch);        }        strcpy(now[1],name[1]);        cnt = 2;        dfs(1);        int q;        scanf("%d",&q);        while(q--)        {            scanf("%s",s);            if(s[0] == 'L')            {                for(int i = 1; i < cnt; i++)                    printf("%s\n",now[i]);            }            else if(s[0] == 'b')            {                scanf("%s",s);                int id = idx[s];                printf("%d\n",son[pre[id]]);            }            else if(s[0] == 'c')            {                scanf("%s%s",s,ch);                int u = idx[s], v = idx[ch];                int g1 = u, g2 = v;                while(u != v) {                    if(dep[u] < dep[v]) v = pre[v];                    else if(dep[u] > dep[v]) u = pre[u];                    else {                        u = pre[u];                        v = pre[v];                    }                }                if(u == g1 || u == g2) u = pre[u];                printf("%s\n", name[u]);            }        }    }    return 0;}
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