Codeforces round #254 (Div. 2) B. dzy loves Chemistry (and query set)

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I didn't make the question last night. I still understood the question wrong when I first read the question. I thought about the order in which I thought, and I thought about it,

It is also misled by the example below.

Question:

There are 1-N kinds of chemicals, a total of M can respond to the reagent, in different order to drop 1-N kinds of reagents into the test tube, if the agent is being dropped into

The number of hazards * 2, otherwise remain unchanged. Ask the maximum risk factor at the end.

Analysis: in fact, this question does not need to consider the order of import. It only needs to be segmented. The result is the power of 1 and 2 of the number of elements in each subset.

 1 #include <iostream> 2 #include <cstring> 3 #include <queue> 4 #include <cmath> 5 #include <cstdio> 6 #include <algorithm> 7 #define LL long long 8 using namespace std; 9 const int maxn = 50 + 10;10 int n, m, bin[maxn], f[maxn], cou;11 int find(int x)12 {13     return bin[x]==x?x:(bin[x]=find(bin[x]));14 }15 void merge(int x, int y)16 {17     int fx = find(x);18     int fy = find(y);19     if(fx != fy)20     {21         bin[fx] = fy;22         cou ++;23     }24 }25 int main()26 {27     int i, x, y;28     LL ans;29     while(~scanf("%d%d", &n, &m))30     {31         cou = 0;32         for(i = 1; i <= n; i++)33         bin[i] = i;34         while(m--)35         {36             cin>>x>>y;37             merge(x, y);38         }39         ans = pow(2, cou);40         cout<<ans<<endl;41     }42     return 0;43 }