PAT 1106 Lowest Price in Supply Chain（DFS树的遍历）

1106 Lowest Price in Supply Chain

A supply chain is a network of retailers（零售商）, distributors（经销商）, and suppliers（供应商）-- everyone involved in moving a product from supplier to customer.

Starting from one root supplier, everyone on the chain buys products from one's supplier in a price P and sell or distribute them in a price that is r% higher than P. Only the retailers will face the customers. It is assumed that each member in the supply chain has exactly one supplier except the root supplier, and there is no supply cycle.

Now given a supply chain, you are supposed to tell the lowest price a customer can expect from some retailers.

Input Specification:

Each input file contains one test case. For each case, The first line contains three positive numbers: N (≤105), the total number of the members in the supply chain (and hence their ID's are numbered from 0 to N−1, and the root supplier's ID is 0); P, the price given by the root supplier; and r, the percentage rate of price increment for each distributor or retailer. Then N lines follow, each describes a distributor or retailer in the following format:

Ki​ ID[1] ID[2] ... ID[Ki​]

where in the i-th line, Ki​ is the total number of distributors or retailers who receive products from supplier i, and is then followed by the ID's of these distributors or retailers. Kj​ being 0 means that the j-th member is a retailer. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print in one line the lowest price we can expect from some retailers, accurate up to 4 decimal places, and the number of retailers that sell at the lowest price. There must be one space between the two numbers. It is guaranteed that the all the prices will not exceed 1010.

Sample Input:

10 1.80 1.00
3 2 3 5
1 9
1 4
1 7
0
2 6 1
1 8
0
0
0

Sample Output:

1.8362 2

总结：这题还是写过类似的题目，还是比较简单的，先dfs遍历树计算叶节点的价格和找出最小价格，最后遍历所有节点计算和最小价格价格相等的节点的数量

 

#include 
#include 
using namespace std;

vector> v;
vector p;
int n;
double price,r,m=0x3f3f3f3f;

void dfs(int node,double y){
    if(v[node].size()==0){//说明该节点是叶节点
        p[node]=y;
        m=m

好好学习，天天向上！

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