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  • 246E Blood Cousins Return

    E. Blood Cousins Return
    time limit per test
    3 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Polycarpus got hold of a family tree. The found tree describes the family relations of n people, numbered from 1 to n. Every person in this tree has at most one direct ancestor. Also, each person in the tree has a name, the names are not necessarily unique.

    We call the man with a number a a 1-ancestor of the man with a number b, if the man with a number a is a direct ancestor of the man with a number b.

    We call the man with a number a a k-ancestor (k > 1) of the man with a number b, if the man with a number b has a 1-ancestor, and the man with a number a is a (k - 1)-ancestor of the 1-ancestor of the man with a number b.

    In the tree the family ties do not form cycles. In other words there isn't a person who is his own direct or indirect ancestor (that is, who is an x-ancestor of himself, for some x, x > 0).

    We call a man with a number a the k-son of the man with a number b, if the man with a number b is a k-ancestor of the man with a number a.

    Polycarpus is very much interested in how many sons and which sons each person has. He took a piece of paper and wrote m pairs of numbers vi, ki. Help him to learn for each pair vi, ki the number of distinct names among all names of the ki-sons of the man with numbervi.

    Input

    The first line of the input contains a single integer n (1 ≤ n ≤ 105) — the number of people in the tree. Next n lines contain the description of people in the tree. The i-th line contains space-separated string si and integer ri (0 ≤ ri ≤ n), where si is the name of the man with a number i, and ri is either the number of the direct ancestor of the man with a number i or 0, if the man with a number i has no direct ancestor.

    The next line contains a single integer m (1 ≤ m ≤ 105) — the number of Polycarpus's records. Next m lines contain space-separated pairs of integers. The i-th line contains integers vi, ki (1 ≤ vi, ki ≤ n).

    It is guaranteed that the family relationships do not form cycles. The names of all people are non-empty strings, consisting of no more than 20 lowercase English letters.

    Output

    Print m whitespace-separated integers — the answers to Polycarpus's records. Print the answers to the records in the order, in which the records occur in the input.

    Sample test(s)
    input
    6 pasha 0 gerald 1 gerald 1 valera 2 igor 3 olesya 1 5 1 1 1 2 1 3 3 1 6 1
    output
    2 2 0 1 0
    input
    6 valera 0 valera 1 valera 1 gerald 0 valera 4 kolya 4 7 1 1 1 2 2 1 2 2 4 1 5 1 6 1
    output
    1 0 0 0 2 0 0
     

    分析:将节点按深度用vector分别存储,将递归时每个节点的头位置和末位置记录下来,搜索某节点n的k儿子时,用头、末位置对可以取的该深度的节点作出限制,然后用set保存名字字符串,set可去重。

    #include<cstdio>
    #include<utility>
    #include<map>
    #include<cstring>
    #include<string>
    #include<vector>
    #include<set>
    #include<algorithm>
    #include<iterator>
    #include<iostream>
    using namespace std;
    
    #define maxn 100010
    typedef pair<int, int> pii;
    
    
    vector<int> adj[maxn];
    vector< pii > point[maxn];
    
    map<pii, int> vis;
    char s[maxn][23];
    int pos[maxn][2], depth[maxn], tot, n, v, k;
    
    void dfs(int k, int d) {
        pos[k][0] = ++tot;
        point[d].push_back(make_pair(tot, k));
        depth[k] = d;
        for (vector<int>::iterator p = adj[k].begin(); p != adj[k].end(); ++p) {
            dfs(*p, d + 1);
        }
        pos[k][1] = ++tot;
    }
    
    int solve() {
        if (vis[make_pair(v, k)])
            return vis[make_pair(v, k)] - 1;
        vector<pii>::iterator l, r;
        set <string> str;
        l = lower_bound(point[depth[v] + k].begin(), point[depth[v] + k].end(), make_pair(pos[v][0], maxn));
        r = lower_bound(point[depth[v] + k].begin(), point[depth[v] + k].end(), make_pair(pos[v][1], 0));
        for (vector<pii>::iterator p = l; p != r; ++p) {
            str.insert(s[(*p).second]);
        }
        return (vis[make_pair(v, k)] = str.size() + 1) - 1;
    }
    
    int main() {
        int m, i, p;
        scanf("%d", &n);
        for (i = 1; i <= n; ++i) {
            scanf("%s%d", &s[i], &p);
            adj[p].push_back(i);
        }
        dfs(0, 0);
        scanf("%d", &m);
        while (m--) {
            scanf("%d%d", &v, &k);
            printf("%d\n", solve());
        }
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/baidongtan/p/2785245.html
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