计算权重以 X 为因子的给定树的节点

给定一棵树，以及所有节点的权重，任务是计算权重可被x整除的节点。
例子：

Input: 
 

x = 5 
Output: 2 
Only the nodes 1 and 2 have weights divisible by 5. 
 

方法：对树和每个节点执行 dfs，检查它的权重是否可以被 x 整除。如果是，则增加计数。
执行：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
long ans = 0;
int x;
vector graph[100];
vector weight(100);
 
// Function to perform dfs
void dfs(int node, int parent)
{
 
    // If weight of the current node
    // is divisible by x
    if (weight[node] % x == 0)
        ans += 1;
 
    for (int to : graph[node]) {
        if (to == parent)
            continue;
        dfs(to, node);
    }
}
 
// Driver code
int main()
{
    x = 5;
 
    // Weights of the node
    weight[1] = 5;
    weight[2] = 10;
    weight[3] = 11;
    weight[4] = 8;
    weight[5] = 6;
 
    // Edges of the tree
    graph[1].push_back(2);
    graph[2].push_back(3);
    graph[2].push_back(4);
    graph[1].push_back(5);
 
    dfs(1, 1);
 
    cout << ans;
 
    return 0;
}

Java

// Java implementation of the approach
import java.util.*;
 
class GFG
{
     
static long ans = 0;
static int x;
static Vector> graph=new Vector>();
static Vector weight=new Vector();
 
// Function to perform dfs
static void dfs(int node, int parent)
{
 
    // If weight of the current node
    // is divisible by x
    if (weight.get(node) % x == 0)
        ans += 1;
 
    for (int i = 0; i < graph.get(node).size(); i++)
    {
        if (graph.get(node).get(i) == parent)
            continue;
        dfs(graph.get(node).get(i), node);
    }
}
 
// Driver code
public static void main(String args[])
{
    x = 5;
 
    // Weights of the node
    weight.add(0);
    weight.add(5);
    weight.add(10);;
    weight.add(11);;
    weight.add(8);
    weight.add(6);
     
    for(int i = 0; i < 100; i++)
    graph.add(new Vector());
 
    // Edges of the tree
    graph.get(1).add(2);
    graph.get(2).add(3);
    graph.get(2).add(4);
    graph.get(1).add(5);
 
    dfs(1, 1);
 
    System.out.println(ans);
}
}
 
// This code is contributed by Arnab Kundu

Python3

# Python3 implementation of the approach
ans = 0
 
graph = [[] for i in range(100)]
weight = [0] * 100
 
# Function to perform dfs
def dfs(node, parent):
    global ans,x
     
    # If weight of the current node
    # is divisible by x
    if (weight[node] % x == 0):
        ans += 1
    for to in graph[node]:
        if (to == parent):
            continue
        dfs(to, node)
 
# Driver code
x = 5
 
# Weights of the node
weight[1] = 5
weight[2] = 10
weight[3] = 11
weight[4] = 8
weight[5] = 6
 
# Edges of the tree
graph[1].append(2)
graph[2].append(3)
graph[2].append(4)
graph[1].append(5)
 
dfs(1, 1)
print(ans)
 
# This code is contributed by SHUBHAMSINGH10

C#

// C# implementation of the approach
using System;
using System.Collections.Generic;
 
class GFG
{
     
static long ans = 0;
static int x;
static List> graph = new List>();
static List weight = new List();
 
// Function to perform dfs
static void dfs(int node, int parent)
{
 
    // If weight of the current node
    // is divisible by x
    if (weight[node] % x == 0)
        ans += 1;
 
    for (int i = 0; i < graph[node].Count; i++)
    {
        if (graph[node][i] == parent)
            continue;
        dfs(graph[node][i], node);
    }
}
 
// Driver code
public static void Main(String []args)
{
    x = 5;
 
    // Weights of the node
    weight.Add(0);
    weight.Add(5);
    weight.Add(10);;
    weight.Add(11);;
    weight.Add(8);
    weight.Add(6);
     
    for(int i = 0; i < 100; i++)
    graph.Add(new List());
 
    // Edges of the tree
    graph[1].Add(2);
    graph[2].Add(3);
    graph[2].Add(4);
    graph[1].Add(5);
 
    dfs(1, 1);
 
    Console.WriteLine(ans);
}
}
 
// This code contributed by Rajput-Ji

Javascript

  
// Javascript implementation of the approach
     
    
let ans = 0;
let x;
 
let graph = new Array(100);
let weight = new Array(100);
for(let i = 0; i < 100; i++)
{
    graph[i] = [];
    weight[i] = 0;
}
 
// Function to perform dfs
function dfs(node, parent)
{
    // If weight of the current node
    // is divisible by x
    if (weight[node] % x == 0)
        ans += 1;
 
    for(let to=0;to<graph[node].length;to++) {
        if(graph[node][to] == parent)
            continue
        dfs(graph[node][to], node); 
    }
}
 
// Driver code
    x = 5;
 
    // Weights of the node
    weight[1] = 5;
    weight[2] = 10;
    weight[3] = 11;
    weight[4] = 8;
    weight[5] = 6;
 
    // Edges of the tree
    graph[1].push(2);
    graph[2].push(3);
    graph[2].push(4);
    graph[1].push(5);
 
    dfs(1, 1);
 
    document.write(ans);
 
    // This code is contributed by Dharanendra L V.
      

输出：

2

复杂度分析：

• 时间复杂度： O(N)。
  在 DFS 中，树的每个节点都被处理一次，因此当树中总共有 N 个节点时，由于 DFS 的复杂性是 O(N)。因此，时间复杂度为 O(N)。
• 辅助空间： O(1)。
  不需要任何额外的空间，因此空间复杂度是恒定的。

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