1114 Family Property

This time, you are supposed to help us collect the data for family-owned property. Given each person's family members, and the estate（房产）info under his/her own name, we need to know the size of each family, and the average area and number of sets of their real estate.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤). Then N lines follow, each gives the infomation of a person who owns estate in the format:

ID Father Mother k Child​1​​⋯Child​k​​ M​estate​​ Area

where ID is a unique 4-digit identification number for each person; Father and Mother are the ID's of this person's parents (if a parent has passed away, -1 will be given instead); k (0) is the number of children of this person; Child​i​​'s are the ID's of his/her children; M​estate​​ is the total number of sets of the real estate under his/her name; and Area is the total area of his/her estate.

Output Specification:

For each case, first print in a line the number of families (all the people that are related directly or indirectly are considered in the same family). Then output the family info in the format:

ID M AVG​sets​​ AVG​area​​

where ID is the smallest ID in the family; M is the total number of family members; AVG​sets​​ is the average number of sets of their real estate; and AVG​area​​ is the average area. The average numbers must be accurate up to 3 decimal places. The families must be given in descending order of their average areas, and in ascending order of the ID's if there is a tie.

Sample Input:

10
6666 5551 5552 1 7777 1 100
1234 5678 9012 1 0002 2 300
8888 -1 -1 0 1 1000
2468 0001 0004 1 2222 1 500
7777 6666 -1 0 2 300
3721 -1 -1 1 2333 2 150
9012 -1 -1 3 1236 1235 1234 1 100
1235 5678 9012 0 1 50
2222 1236 2468 2 6661 6662 1 300
2333 -1 3721 3 6661 6662 6663 1 100

 

Sample Output:

3
8888 1 1.000 1000.000
0001 15 0.600 100.000
5551 4 0.750 100.000

题意：

　　寻找一个家族人员的最小编号，总人数，AVGsets， AVGarea。

思路：

　　将每一个家族中的人归并的一个子集中，这道题要求寻找最小的编号因此Union的时候要使编号小的成为编号大的祖先结点。

Code：

#include <bits/stdc++.h>

using namespace std;

vector<int> fa(10005, 0);

int findFather(int x) {
    int a = x;
    while (x != fa[x]) {
        x = fa[x];
    }
    // 路径压缩
    while (a != fa[a]) {
        int z = a;
        a = fa[a];
        fa[z] = x;
    }
    return x;
}

void Union(int x, int y) {
    int faX = findFather(x);
    int faY = findFather(y);
    if (faX < faY)
        fa[faY] = faX;
    else
        fa[faX] = faY;
}

struct Family {
    int index = 0;
    double sum_estate = 0;
    double sum_area = 0;
    double AVGarea = 0;
    double AVGsets = 0;
    bool haveMerged = false;
    set<int> people;
};

bool cmp(Family x, Family y) {
    if (x.AVGarea == y.AVGarea)
        return x.index < y.index;
    else
        return x.AVGarea > y.AVGarea;
}

int main() {
    int n;
    cin >> n;
    Family fam[10005];
    for (int i = 0; i < 10005; ++i) fa[i] = i;
    for (int i = 0; i < n; ++i) {
        int id, father, mather, nums, child, estate, area;
        cin >> id >> father >> mather >> nums;
        set<int> people;
        people.insert(id);
        if (father != -1) {
            people.insert(father);
            Union(id, father);
        }
        if (mather != -1) {
            people.insert(mather);
            Union(id, mather);
        }
        for (int j = 0; j < nums; ++j) {
            cin >> child;
            people.insert(child);
            Union(id, child);
        }
        cin >> estate >> area;
        int index = findFather(id);
        fam[index].sum_estate += estate;
        fam[index].sum_area += area;
        fam[index].index = index;
        for (int p : people) fam[index].people.insert(p);
    }
    vector<Family> ans;
    for (int i = 0; i < 10005; ++i) {
        if (fam[i].sum_estate > 0) {
            int index = findFather(i);
            fam[index].haveMerged = true;
            if (i != index) {
                fam[index].sum_area += fam[i].sum_area;
                fam[index].sum_estate += fam[i].sum_estate;
                fam[index].index = index;
                for (int j : fam[i].people) fam[index].people.insert(j);
            }
        }
    }
    for (int i = 0; i < 10005; ++i) {
        if (fam[i].haveMerged) ans.push_back(fam[i]);
    }
    for (auto& it : ans) {
        it.AVGarea = it.sum_area / it.people.size();
        it.AVGsets = it.sum_estate / it.people.size();
    }
    sort(ans.begin(), ans.end(), cmp);
    cout << ans.size() << endl;
    for (auto it : ans) {
        printf("%04d %d %.3f %.3f
", it.index, it.people.size(), it.AVGsets,
               it.AVGarea);
    }
    return 0;
}