1 #include
     
       2 #include
      
        3 int set[10000005]; 4 int count; 5 #define mod 1000000007 6  7 int find(int x) 8 { 9     int r=x;10     while(r!=set[r])11     r=set[r];12     int i=x;13     while(i!=r)14     {15         int j=set[i];16         set[i]=r;17         i=j;18     }19     return r;20 }21 22 void merge(int x,int y)23 {24     int fx=find(x);25     int fy=find(y);26     if(fx!=fy)27     {28         set[fx]=fy;29         count++;30     }31 }32 33 long long exp(int n){34     long long sum=1, tmp=26;35     while(n){36         if(n&1) //n%2==137         {38             sum = sum*tmp;39             sum %= mod;40         }41         tmp = (tmp*tmp)%mod;42         n>>=1;  //  n/=2;43     }44     return sum;45 }46 47 int main()48 {49     int n,m,l,r;50     while(scanf("%d%d",&n,&m)!=EOF)51     {52         count=0;53         for(int i=0;i<=n;i++)//i=0,错在i=154         set[i]=i;55         for(int i=1;i<=m;i++)56         {57             scanf("%d%d",&l,&r);58             merge(l-1,r);//若果是l-1,上边初始化就从0开始，如果用merge（l，r+1）,初始化i是1到n+159         }60         printf("%lld\n",exp(n-count)%mod);61     }62     return 0;63 }