zoukankan      html  css  js  c++  java
  • Codeforces 429 A. Xor-tree


    下来的第一次相遇是在不翻盖的同一节点,递归可以是....

    A. Xor-tree
    time limit per test
    1 second
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Iahub is very proud of his recent discovery, propagating trees. Right now, he invented a new tree, called xor-tree. After this new revolutionary discovery, he invented a game for kids which uses xor-trees.

    The game is played on a tree having n nodes, numbered from 1 to n. Each node i has an initial value initi, which is either 0 or 1. The root of the tree is node 1.

    One can perform several (possibly, zero) operations on the tree during the game. The only available type of operation is to pick a nodex. Right after someone has picked node x, the value of node x flips, the values of sons of x remain the same, the values of sons of sons of x flips, the values of sons of sons of sons of x remain the same and so on.

    The goal of the game is to get each node i to have value goali, which can also be only 0 or 1. You need to reach the goal of the game by using minimum number of operations.

    Input

    The first line contains an integer n (1 ≤ n ≤ 105). Each of the next n - 1 lines contains two integers ui and vi (1 ≤ ui, vi ≤ nui ≠ vi) meaning there is an edge between nodes ui and vi.

    The next line contains n integer numbers, the i-th of them corresponds to initi (initi is either 0 or 1). The following line also contains ninteger numbers, the i-th number corresponds to goali (goali is either 0 or 1).

    Output

    In the first line output an integer number cnt, representing the minimal number of operations you perform. Each of the next cnt lines should contain an integer xi, representing that you pick a node xi.

    Sample test(s)
    input
    10
    2 1
    3 1
    4 2
    5 1
    6 2
    7 5
    8 6
    9 8
    10 5
    1 0 1 1 0 1 0 1 0 1
    1 0 1 0 0 1 1 1 0 1
    
    output
    2
    4
    7

    #include <iostream>
    #include <cstdio>
    #include <cstring>
    #include <algorithm>
    #include <vector>
    
    using namespace std;
    
    int n,init[110000],goal[110000];
    vector<int> g[110000],ans;
    
    void dfs(int u,int fa,int c1,int c2)
    {
        if(c1) init[u]^=1;
        if(init[u]!=goal[u])
        {
            c1^=1; ans.push_back(u);
        }
        for(int i=0;i<g[u].size();i++)
        {
            int v=g[u][i];
            if(v==fa) continue;
            dfs(v,u,c2,c1);
        }
    }
    
    int main()
    {
        scanf("%d",&n);
        for(int i=1;i<n;i++)
        {
            int a,b;
            scanf("%d%d",&a,&b);
            g[a].push_back(b);
            g[b].push_back(a);
        }
        g[0].push_back(1);
        for(int i=1;i<=n;i++)
            scanf("%d",init+i);
        for(int i=1;i<=n;i++)
            scanf("%d",goal+i);
        dfs(0,0,0,0);
        printf("%d
    ",(int)ans.size());
        for(int i=0;i<ans.size();i++)
            printf("%d
    ",ans[i]);
        return 0;
    }
    


    版权声明:本文博客原创文章。博客,未经同意,不得转载。

  • 相关阅读:
    数学思想方法-python计算战(8)-机器视觉-二值化
    04-05组合问题_算法训练
    至HDFS附加内容
    HDU 1010 Tempter of the Bone heuristic 修剪
    二叉树3种遍历的非递归算法
    [Ramda] R.project -- Select a Subset of Properties from a Collection of Objects in Ramda
    [Ramda] Refactor a Promise Chain to Function Composition using Ramda
    [SVG] Combine Multiple SVGs into an SVG Sprite
    [Ramda] Difference between R.converge and R.useWith
    [Ramda] Refactor to a Point Free Function with Ramda's useWith Function
  • 原文地址:https://www.cnblogs.com/mengfanrong/p/4656737.html
Copyright © 2011-2022 走看看