【Luogu】P4208最小生成树计数（状压乱搞）

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cctype>
#include<cstdlib>
#define maxn 10000
#define mod 31011
using namespace std;
inline long long read(){
    long long num=0,f=1;
    char ch=getchar();
    while(!isdigit(ch)){
        if(ch==‘-‘)    f=-1;
        ch=getchar();
    }
    while(isdigit(ch)){
        num=num*10+ch-‘0‘;
        ch=getchar();
    }
    return num*f;
}

struct Edge{
    int from,to,val;
}edge[maxn],q[maxn],d[maxn];
bool cmp(Edge a,Edge b){    return a.val<b.val;    }
int head[maxn],num;
inline void add(int from,int to,int val){
    edge[++num]=(Edge){head[from],to,val};
    head[from]=num;
}

bool vis[maxn];
int sum[maxn];
int w[maxn];
int size;
struct fus{
    int father[maxn];
    inline void clear(int n){    for(int i=1;i<=n;++i)    father[i]=i;    }
    int find(int x){
        if(father[x]!=x)    father[x]=find(father[x]);
        return father[x];
    }
    inline void unionn(int x,int y){
        x=find(x);    y=find(y);
        father[y]=x;
    }
}c,r,right;

inline int getlen(int x){
    int ans=0;
    while(x){
        if(x&1)    ans++;
        x>>=1;
    }
    return ans;
}

int ans[maxn];
int pre[maxn];

void copy(int x,int *a,int *b){    for(int i=1;i<=x;++i)    a[i]=b[i];}

int main(){
    int n=read(),m=read();
    for(int i=1;i<=m;++i)    q[i]=(Edge){read(),read(),read()};
    c.clear(n);
    sort(q+1,q+m+1,cmp);
    int cnt=0,last=0,now=0;
    for(int i=1;i<=m;++i){
        //离散化 
        now=q[i].val;
        if(q[i].val==last)    q[i].val=size;
        else                 q[i].val=++size;
        last=now;
        
        int from=q[i].from,to=q[i].to;
        if(c.find(from)==c.find(to))    continue;
        c.unionn(from,to);
        vis[q[i].val]=1;
        sum[q[i].val]++;
        cnt++;
        if(cnt==n-1)    break;
    }
    if(cnt<n-1){
        printf("0");
        return 0;
    }
    c.clear(n);
    cnt=0;
    int maxval=0;
    for(int i=1;i<=m;++i)
        if(vis[q[i].val]){
            d[++cnt]=q[i];
            w[q[i].val]++;
            maxval=max(maxval,q[i].val);
        }
    last=0;
    for(int i=1;i<=maxval;++i){
        int Max=1<<w[d[last+1].val];
        copy(n,right.father,c.father);
        for(int j=0;j<Max;++j){
            if(getlen(j)!=sum[d[last+1].val])    continue;
            bool flag=0;
            copy(n,r.father,c.father);
            for(int k=0;(1<<k)<=j;++k)
                if(j&(1<<k)){
                    int ret=(k+1)+last;
                    if(r.find(d[ret].from)==r.find(d[ret].to)){
                        flag=1;
                        break;
                    }
                    r.unionn(d[ret].from,d[ret].to);
                }
            if(flag==0){
                ans[d[last+1].val]++;
                copy(n,right.father,r.father);
            }
        }
        copy(n,c.father,right.father);
        last+=w[d[last+1].val];
    }
    for(int i=1;i<=maxval;++i)
        if(w[i]){
            last=i;
            break;
        }
    for(int i=last;i<=maxval;++i){
        if(ans[i]&&i!=last){
            ans[i]=(ans[i]*ans[last])%mod;
            last=i;
        }
    }
    printf("%d\n",ans[last]);
    return 0;
}