HDU - 6836 Expectation

传送门：HDU - 6836

思路分析

先计算出总的生成树个数，再按位计算权值和

AC代码

#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pb push_back
#define mp make_pair
#define fun function
#define sz(x) (x).size()
#define lowbit(x) (x)&(-x)
#define all(x) (x).begin(),(x).end()
#define mem(a,b) memset(a,b,sizeof(a))

namespace FastIO {
#define BUF_SIZE 100000
#define OUT_SIZE 100000
    bool IOerror=0;
    inline char nc() {
        static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE;
        if(p1==pend) {
            p1=buf;
            pend=buf+fread(buf,1,BUF_SIZE,stdin);
            if(pend==p1) {
                IOerror=1;
                return -1;
            }
        }
        return *p1++;
    }
    inline bool blank(char ch) {
        return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';
    }
    template<class T> inline bool read(T &x) {
        bool sign=0;
        char ch=nc();
        x=0;
        for(; blank(ch); ch=nc());
        if(IOerror)return false;
        if(ch=='-')sign=1,ch=nc();
        for(; ch>='0'&&ch<='9'; ch=nc())x=x*10+ch-'0';
        if(sign)x=-x;
        return true;
    }
    template<class T,class... U>bool read(T& h,U&... t) {
        return read(h)&&read(t...);
    }
#undef OUT_SIZE
#undef BUF_SIZE
};
using namespace std;
using namespace FastIO;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int INF = 0x3f3f3f3f;
const int N = 111;
const int M = 1e4+10;
const int mod = 998244353;

#define int long long
int n,m;
int a[M],b[M],c[M],g[N][N];

ll qpow(ll x,int n) {
    ll res=1;
    while(n) {
        if(n&1) res = res*x%mod;
        x=x*x%mod;
        n/=2;
    }
    return res;
}

void add(int u,int v) {
    g[u][u]++;
    g[v][v]++;
    g[u][v]--;
    g[v][u]--;
}

int gauss() {
    int res=1;
    for(int i=1; i<n; i++) {
        for(int j=i+1; j<n; j++) {
            while(g[j][i]) {
                int t=g[i][i]/g[j][i];
                for(int k=i; k<n; k++)    g[i][k]=(g[i][k]-t*g[j][k]+mod)%mod;
                swap(g[i],g[j]);
                res=-res;
            }
        }
        res=(res*g[i][i])%mod;
    }
    return (res+mod)%mod;
}


signed main() {

#ifdef xiaofan
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
#endif

    int T;
    read(T);
    while(T--) {
        mem(g,0);
        read(n,m);
        for(int i=1; i<=m; i++) {
            read(a[i],b[i],c[i]);
            add(a[i],b[i]);
        }
        ll tot = gauss();
        ll ans = 0;
        for(int i=0;i<=31;i++){
            mem(g,0);
            for(int j=1;j<=m;j++){
                if((c[j]>>i)&1LL) add(a[j],b[j]);
            }
            ans = (ans + gauss()*(1LL<<i))%mod;
        }
        ans = ans * qpow(tot,mod-2) %mod;
        printf("%lld\n",ans);
    }



    return 0;
}