4569: [Scoi2016]萌萌噠 倍增+並查集

好神的一道題，不會做。
%Claris

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

const int N=100005;
const int mod=1000000007;
int n,m,ans;
bool vis[N];
int f[17][N];

inline int read()
{
    int a=0,f=1; char c=getchar();
    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}
    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}
    return a*f;
}

int find(int i,int j)
{
    return f[i][j]==j?j:f[i][j]=find(i,f[i][j]);
}

inline void merge(int k,int a,int b)
{
    int p=find(k,a),q=find(k,b);
    if (p==q) return;
    f[k][p]=f[k][q];
    if (!k) return;
    k--;
    merge(k,a,b); merge(k,a+(1<<k),b+(1<<k));
}

int main()
{
    n=read(); m=read();
    if (n==1) {puts("10"); return 0;}
    for (int i=0;(1<<i)<=n;i++)
        for (int j=1;j+(1<<i)-1<=n;j++)
            f[i][j]=j;
    for (int i=1;i<=m;i++)
    {
        int l1=read(),r1=read(),l2=read(),r2=read(),k=log2(r1-l1+1);
        merge(k,l1,l2); merge(k,r1-(1<<k)+1,r2-(1<<k)+1);
    }
    ans=9;
    vis[find(0,1)]=1;
    for (int i=2;i<=n;i++)
        if (!vis[find(0,i)])
        {
            vis[find(0,i)]=1;
            ans=(long long)ans*10%mod;
        }
    cout << ans << endl;
    return 0;
}