【搜索】Day6-C

链接

C

题目描述

一棵树删去任意条边，可以得到若干棵新树。
若使让每棵新树的节点数相同。问有多少种方法分割这棵树。

思路

来自大佬

代码

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<cmath>

using namespace std;

struct node
{
    
    
	int to, next;
}g[2000006];

int n, t, num, sum, ans;
int y[1000006], h[1000006], size[1000006];

int read() 
{
    
    
	int x = 0, flag = 1; char ch = getchar();
	while (ch < '0' || ch > '9') {
    
    if (ch == '-') flag = -1; ch = getchar();}
	while (ch >= '0' && ch <= '9'){
    
    x = x * 10 + ch - '0'; ch = getchar();}
	return x * flag;
}

void add(int x, int y)
{
    
    
	g[++t] = (node){
    
    y, h[x]}; h[x] = t;
	g[++t] = (node){
    
    x, h[y]}; h[y] = t;
}

void dfs(int x, int fath)
{
    
    
	size[x] = 1;
	for(int i = h[x]; i; i = g[i].next)
	{
    
    
		int to = g[i].to;
		if(to == fath) continue;
		dfs(to, x);
		size[x] += size[to];
	}
}

int main()
{
    
    
	n = read();
	for(int i = 1; i < n; ++i)
	{
    
    
		int x, y;
		x = read(); y = read();
		add(x, y);
	}
	dfs(1, 0);
	for(int i = 1; i <= floor(sqrt(n)); ++i)
	{
    
    
		if(i * i == n) y[++num] = i;
		else if(n % i == 0) {
    
    
			y[++num] = i;
			y[++num] = n / i;
		}
	}
	for(int i = 1; i <= num; ++i) {
    
    
		for(int j = 1; j <= n; ++j)
			if(size[j] % y[i] == 0) sum++;
		if(sum == n / y[i]) ans++;
		sum = 0;	
	}
	printf("%d", ans);
	return 0;
}