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  • Codeforces Round #254(div2)B

    就是看无向图有几个连通块,答案就是2n-num

    范围很小,就用矩阵来存图减少代码量。

    #include<iostream>
    #include<cstdio>
    #include<cstdlib>
    #include<cstring>
    #include<cmath>
    #include<map>
    #include<set>
    #include<vector>
    #include<algorithm>
    #include<stack>
    #include<queue>
    using namespace std;
    #define INF 1000000000
    #define eps 1e-8
    #define pii pair<int,int>
    #define LL long long int
    int n,m,maps[55][55],a,b;
    int mark[55],num;
    void dfs(int x)
    {
        mark[x]=1;
        for(int i=1;i<=n;i++)
        {
            if(mark[i]==0&&maps[x][i])
            {
                dfs(i);
            }
        }
    }
    int main()
    {
        //freopen("in1.txt","r",stdin);
        //freopen("out.txt","w",stdout);
        scanf("%d%d",&n,&m);
        for(int i=1;i<=m;i++)
        {
            scanf("%d%d",&a,&b);
            maps[a][b]=maps[b][a]=1;
        }
        for(int i=1;i<=n;i++)
        {
            if(!mark[i])
            {
                num++;
                dfs(i);
            }
        }
        printf("%I64d
    ",(LL)1<<(n-num));
        //fclose(stdin);
        //fclose(stdout);
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/zywscq/p/3921094.html
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