HDU 4409 Family Name List ( 模拟 + LCA)

　　昨晚脑子发涨，代码写的跟坨屎的，到底没过，今天早晨来看了看，查了几个bug过了。。。

纯模拟+LCA找最近公共祖先，需要注意的几个地方：

1、出处顺序，可以用dfs输出，不过每个dfs里面要开一个vector<>，然后排序。

2、b操作可能出现询问Mr.X，Mr.X的brother个数为1

3、c操作时LCA不能是他两个本身。可以开一个pre，如果是他俩中的一个，再往前找一个就可以了。

200+行的渣代码：

 

//#pragma comment(linker,"/STACK:327680000,327680000")
#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
#include <stack>
#include <map>
#include <queue>

#define CL(arr, val) memset(arr, val, sizeof(arr))
#define REP(i, n)for((i) = 0; (i) < (n); ++(i))
#define FOR(i, l, h)for((i) = (l); (i) <= (h); ++(i))
#define FORD(i, h, l)for((i) = (h); (i) >= (l); --(i))
#define L(x)(x) << 1
#define R(x)(x) << 1 | 1
#define MID(l, r)(l + r) >> 1
#define Min(x, y)x < y ? x : y
#define Max(x, y)x < y ? y : x
#define E(x)(1 << (x))
#define iabs(x) (x) < 0 ? -(x) : (x)
#define OUT(x)printf("%I64d\n", x)
#define lowbit(x)(x)&(-x)
#define Read()freopen("data.in", "r", stdin)
#define Write()freopen("data.out", "w", stdout);

const double eps = 1e-10;
typedef long long LL;
const int inf = ~0u>>2;

using namespace std;

const int N = 30010;

struct People {
    string name;
    int lv;
    int num;
    bool operator < (const People cmp) const {
        return name < cmp.name;
    }
}p[N];


int child[N];
int pre[N], fa[N];
int pp[N];
int n;

string anc, tmp, tmp2;
map<string, int> numb;


struct pnode {
    int to;
    int next;
} g[N];

int head[N], t;
class Graph {
public:
    void init() {CL(head, -1); t = 0;}
    void add(int u, int v) {g[t].to = v; g[t].next = head[u]; head[u] = t++;}
} G;


int D[N<<1], E[N<<1], R[N<<1];
int Min[N<<1][21];

class RMQ {
public:

    void build(int n) {
        int i, j, m;
        for(i = 1; i <= n; ++i) Min[i][0] = i;
        m = int(log(double(n))/log(2.0));
        FOR(j, 1, m) {
            FOR(i, 1, n - (1<<j) + 1) {
                if(D[Min[i][j-1]] < D[Min[i+(1<<(j-1))][j-1]]) {
                    Min[i][j] = Min[i][j-1];
                } else {
                    Min[i][j] = Min[i+(1<<(j-1))][j-1];
                }

            }
        }
    }

    int query(int s, int e) {
        int k = log(double(e - s + 1))/log(2.0);
        if(D[Min[s][k]] < D[Min[e-(1<<k) + 1][k]])   return  Min[s][k];
        else    return Min[e-(1<<k) + 1][k];
    }
} Q;


class LCA {
public:
    int cnt;
    bool vis[N];

    void init() {
        CL(D, 0);
        CL(E, 0); CL(R, 0);
        CL(vis, 0); cnt = 0;
    }

    void dfs(int t, int dep) {
        D[++cnt] = dep;
        E[cnt] = t;

        if(!vis[t]) {
            R[t] = cnt;
            vis[t] = true;
        }

        for(int i = head[t]; i != -1; i = g[i].next) {
            dfs(g[i].to, dep + 1);
            D[++cnt] = dep;
            E[cnt] = t;
        }
    }
    void build() {
        init();
        dfs(0, 0);
        Q.build(cnt);
    }
    int query(int x, int y) {
        x = R[x], y = R[y];
        if(x > y)   swap(x, y);
        return E[Q.query(x, y)];
    }
}LCA;


void init() {
    CL(child, 0); CL(pre, -1);
    CL(fa, 0);
    numb.clear();
    G.init();
}

void read_data() {
    int i, j;
    cin >> anc;
    p[0].name = anc;
    p[0].lv = 0;
    p[0].num = 0;
    for(i = 1; i < n; ++i) {
        cin >> tmp;
        j = 0;
        while(tmp[j] == '.' && j < static_cast<int>(tmp.size())) ++j;
        p[i].lv = j;
        p[i].num = i;
        p[i].name = tmp.substr(j);
        numb[p[i].name] = i;
        fa[j] = i; pre[i] = fa[j-1];
        G.add(fa[j-1], i);
        child[fa[j-1]]++;
    }
}

void print(People a) {
    int i = a.lv;
    while(i--)  putchar('.');
    cout << a.name << endl;
}

void List(int t) {
    print(p[t]);
    vector<People> q;
    int r = 0, i;
    for(i = head[t]; i != -1; i = g[i].next) {
        q.push_back(p[g[i].to]);
        r++;
    }
    if(r == 0)  return ;
    sort(q.begin(), q.end());
    for(i = 0; i < r; ++i) {
        List(q[i].num);
    }
}

char op[2];
void solve() {
    int q, i, j, pos;
    scanf("%d", &q);
    while(q--) {
        scanf("%s", op);
        if(op[0] == 'L') {
            List(0);
        } else if(op[0] == 'b') {
            cin >> tmp;
            i = numb[tmp];
            if(i == 0)  puts("1");
            else    printf("%d\n", child[pre[i]]);
        } else {
            cin >> tmp >> tmp2;
            i = numb[tmp]; j = numb[tmp2];
            pos = LCA.query(i, j);
            if(pos == i)    pos = pre[i];
            if(pos == j)    pos = pre[j];
            cout << p[pos].name << endl;
        }
    }
}

int main() {
    //Read();

    while(scanf("%d", &n), n) {
        init();
        read_data();

        LCA.build();
        solve();
    }
    return 0;

}