Codeforces 839C Journey

本文提供了一种解决CodeForces平台上的C题的方法,采用广度优先搜索算法(BFS)计算图中所有节点到根节点的加权距离,并通过遍历每个节点来求得最终答案。

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题目链接:

http://codeforces.com/contest/839/problem/C

题解:

昨晚脑子一抽,算了半天的平均期望。。。

代码:

#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
#define met(a,b) memset(a,b,sizeof(a))
const int maxn = 1e5+10;
vector<int> p[maxn];
vector<int> l;
int visited[maxn];
int dis[maxn];
double EX[maxn];
double ans;
queue<int> q;

void bfs()
{
    while(!q.empty())
        q.pop();
    dis[1]=0;
    EX[1]=1;
    visited[1]=1;
    q.push(1);
    while(!q.empty())
    {
        int x=q.front();
        visited[x]=1;
        q.pop();
        l.clear();
        for(int i=0;i<p[x].size();i++)
        {
            int y=p[x][i];
            if(!visited[y])
                l.push_back(y);
        }
        if(l.size()==0)
            ans+=EX[x]*dis[x];
        else
        {
            for(int i=0;i<l.size();i++)
            {
                EX[l[i]]=EX[x]/l.size();
                dis[l[i]]=dis[x]+1;
                q.push(l[i]);
            }
        }
    }
}



int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n-1;i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        p[x].push_back(y);
        p[y].push_back(x);
    }
    ans=0;
    met(visited,0);
    met(dis,0);
    met(EX,0);
    bfs();
    printf("%f\n",ans);
}
### Codeforces Problem 1332C Explanation The provided references pertain specifically to problem 742B on Codeforces rather than problem 1332C. For an accurate understanding and solution approach for problem 1332C, it's essential to refer directly to its description and constraints. However, based on general knowledge regarding competitive programming problems found on platforms like Codeforces: Problem 1332C typically involves algorithmic challenges that require efficient data structures or algorithms such as dynamic programming, graph theory, greedy algorithms, etc., depending upon the specific nature of the task described within this particular question[^6]. To provide a detailed explanation or demonstration concerning **Codeforces problem 1332C**, one would need direct access to the exact statement associated with this challenge since different tasks demand tailored strategies addressing their unique requirements. For obtaining precise details about problem 1332C including any sample inputs/outputs along with explanations or solutions, visiting the official Codeforces website and navigating to contest number 1332 followed by examining section C is recommended. ```python # Example pseudo-code structure often seen in solving competitive coding questions. def solve_problem_1332C(input_data): # Placeholder function body; actual logic depends heavily on the specifics of problem 1332C. processed_result = process_input(input_data) final_answer = compute_solution(processed_result) return final_answer input_example = "Example Input" print(solve_problem_1332C(input_example)) ```
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