#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define X first #define Y second #define pb push_back #define rep(X,Y) for (int (X) = 0;(X) < (int)(Y);++(X)) #define reps(X,S,Y) for (int (X) = (int)(S);(X) < (int)(Y);++(X)) #define rrep(X,Y) for (int (X) = (int)(Y)-1;(X) >=0;--(X)) #define rreps(X,S,Y) for (int (X) = (int)(Y)-1;(X) >= (int)(S);--(X)) #define repe(X,Y) for ((X) = 0;(X) < (Y);++(X)) #define peat(X,Y) for (;(X) < (Y);++(X)) #define all(X) (X).begin(),(X).end() #define rall(X) (X).rbegin(),(X).rend() #define eb emplace_back #define UNIQUE(X) (X).erase(unique(all(X)),(X).end()) #define Endl endl #define NL <<"\n" #define cauto const auto using namespace std; using ll=long long; using pii=pair; using pll=pair; template using vv=vector>; template inline bool MX(T &l,const T &r){return l inline bool MN(T &l,const T &r){return l>r?l=r,1:0;} //#undef NUIP #ifdef NUIP #include "benri.h" #else #define out(args...) #endif void ouT(ll x,int d=3){auto re=to_string(x);if((int)re.size()>d) re=x>0?"oo":"-oo";cout<vector table(int n, T v){ return vector(n, v);} template auto table(int n, Args... args){auto val = table(args...); return vector(n, move(val));} #endif template pair operator+(const pair &p,const pair &q){ return {p.X+q.X,p.Y+q.Y};} template pair& operator+=(pair &p,const pair &q){ p.X+=q.X; p.Y+=q.Y; return p;} template pair operator-(const pair &p,const pair &q){ return {p.X-q.X,p.Y-q.Y};} template pair& operator-=(pair &p,const pair &q){ p.X-=q.X; p.Y-=q.Y; return p;} template istream& operator>>(istream &is, pair &p){ is>>p.X>>p.Y; return is;} template T read(){ T re; cin>>re; return move(re);} template T read(const T &dec){ T re; cin>>re; return re-dec;} template vector readV(const int sz){ vector re(sz); for(auto &x:re) x=read(); return move(re);} template vector readV(const int sz, const T &dec){ vector re(sz); for(auto &x:re) x=read(dec); return move(re);} vv readG(const int &n,const int &m){ vv g(n); rep(_,m){ cauto a=read(1),b=read(1); g[a].pb(b); g[b].pb(a);} return move(g);} vv readG(const int &n){ return readG(n,n-1);} #define TT cauto TTT=read();rep(_,TTT) const ll MOD=1e9+7; //998244353; struct UF{ vector data; UF(const int &size):data(size,-1){} int unite(int x, int y){ x=root(x); y=root(y); if(x==y) return 0; if(-data[y]>-data[x]) swap(x,y); data[x]+=data[y]; data[y]=x; return y+1; } bool findSet(const int &x, const int &y){ return root(x)==root(y);} int root(const int &x){ return data[x]<0?x:data[x]=root(data[x]);} int size(const int &x){ return -data[root(x)];} int size(){ return count_if(all(data),[](const int &x){ return x<0;});}; //unverified int operator()(const int &x, const int &y){ return unite(x,y);} int operator()(const pii &xy){ return unite(xy.X,xy.Y);} int operator[](const int &x){ return root(x);} bool operator[](const pii &xy){ return findSet(xy.X,xy.Y);} }; ll modpow_(ll r,ll n,ll m=MOD){ ll re=1,d=r%m; if(n<0)(n%=m-1)+=m-1; for(;n;n/=2){ if(n&1)(re*=d)%=m; (d*=d)%=m; } return re; } template struct ModInt{ int v; ModInt(int v=0):v(v){} ModInt operator+(const ModInt &n)const{return v+n.v=mod) v-=mod; return *this;} ModInt& operator-=(const ModInt &n){v-=n.v; if(v<0) v+=mod; return *this;} ModInt& operator*=(const ModInt &n){v=ll(v)*n.v%mod; return *this;} ModInt& operator/=(const ModInt &n){v=ll(v)*modpow_(n.v,-1,mod)%mod; return *this;} ModInt& operator+=(const ll &n){v+=n; if(v>=mod) v-=mod; return *this;} ModInt& operator-=(const ll &n){v-=n; if(v<0) v+=mod; return *this;} ModInt& operator*=(const ll &n){v=ll(v)*n%mod; return *this;} ModInt& operator/=(const ll &n){v=ll(v)*modpow_(n,-1,mod)%mod; return *this;} bool operator==(const ModInt &n)const{return v==n.v;}; bool operator!=(const ModInt &n)const{return v!=n.v;}; ModInt& operator++(){ return operator+=(1); } ModInt& operator--(){ return operator-=(1); } ModInt operator++(int i){ ModInt tmp(*this); operator++(); return tmp; } ModInt operator--(int i){ ModInt tmp(*this); operator--(); return tmp; } }; #ifdef NUIP class MINT_FRAC____{ public: unordered_map dict; MINT_FRAC____(int n){ rep(p,n+1)reps(q,1,n+1)if(__gcd(p,q)==1){ dict[1ll*p*modpow_(q,-1)%MOD]=pii(p,q); dict[MOD-1ll*p*modpow_(q,-1)%MOD]=pii(-p,q); } } } Il1Il1Il1(1000); template ostream& operator<<(ostream &os,const ModInt &n){if(Il1Il1Il1.dict.count(n.v)) os< ostream& operator<<(ostream &os,const ModInt &n){return os< ModInt operator+(const ll &n,const ModInt &m){return m.v+n ModInt operator-(const ll &n,const ModInt &m){return n-m.v<0 ? n-m.v+mod : n-m.v;} template ModInt operator*(const ll &n,const ModInt &m){return ll(m.v)*(n%mod)%mod;} template ModInt operator/(const ll &n,const ModInt &m){return ModInt(n%mod)/m;} typedef ModInt mint; template ModInt modpow(ModInt r,ll n){ ModInt re(1); if(n<0)(n%=mod-1)+=mod-1; for(;n;n/=2){if(n&1) re*=r; r*=r;} return re;} vector fact,finv,inv; mint comb(ll n,ll r){ if(n &re,int n){ re.resize(n+1); re[1]=1; for(int i=2;i<=n;++i)re[i]=re[MOD%i]*(MOD-MOD/i);} void Facts(vector &re,int n){ re.resize(n+1); re[0]=1; rep(i,n)re[i+1]=re[i]*(i+1);} void Factinvs(vector &re,const vector &inv,int n){ re.resize(n+1); re[0]=1; rep(i,n)re[i+1]=re[i]*inv[i+1];} public: Doralion(int n){ Modinvs(inv,n); Facts(fact,n); Factinvs(finv,inv,n);} } doralion(1123456); using pmm=pair; mint modpow(ll r,ll n){ return modpow_(r,n);} mint solve(const vv &g,const ll t){ const int n=g.size(); vector nums(n); vector cs(n); vector usd(n); { cauto dfs= [&](auto &&dfs,int v)->void{ for(cauto &[u,s]:g[v]){ if(!MX(usd[u],1)) continue; nums[u]=s-nums[v]; cs[u]=1-cs[v]; dfs(dfs,u); } }; rep(v,n)if(MX(usd[v],1)) dfs(dfs,v); } out(nums,1); UF uf(n); rep(v,n)for(cauto &[u,s]:g[v]) uf(u,v); vector isB(n,1); vector difs(n); rep(v,n)for(cauto &[u,s]:g[v])if(cs[u]==cs[v]){ isB[uf[v]]=0; if(cs[v]) difs[uf[v]]=s-nums[u]-nums[v]; else difs[uf[v]]=nums[u]+nums[v]-s; } out(difs,1); for(cauto &v:difs)if(v%2) return 0; rep(v,n){ if(cs[v]) nums[v]+=difs[uf[v]]/2; else nums[v]-=difs[uf[v]]/2; } out(nums,1); rep(v,n)for(cauto &[u,s]:g[v]){ if(nums[u]+nums[v]!=s) return 0; } const ll INF=1e16; vector mns(n+n,INF),mxs(n+n,-INF); rep(v,n){ MN(mns[2*uf[v]+cs[v]],nums[v]); MX(mxs[2*uf[v]+cs[v]],nums[v]); } out(nums,cs,isB,mns,mxs,1); vector re(2,1); rep(i,2){ //t-i; rep(v,n)if(uf[v]==v){ out(v,t-i,1); if(!isB[v]){ if(mns[2*v]<=0 || mns[2*v+1]<=0 || mxs[2*v]>t-i || mxs[2*v+1]>t-i){ re[i]=0; break; } continue; } // 1<=mn0+x && mx0+x<=t-i // 1<=mn1-x && mx1-x<=t-i cauto lb=max(1-mns[2*v], mxs[2*v+1]-t+i); cauto ub=min(t-i-mxs[2*v], mns[2*v+1]-1); re[i]*=max(0ll,ub-lb+1)%MOD; } } out(re,1); return re[0]-re[1]; } int main(){ ios_base::sync_with_stdio(false); cin.tie(0); cout< g(n); rep(_,m){ cauto v=read(1); cauto u=read(1); cauto w=read(0); g[u].eb(v,w); g[v].eb(u,w); } cout<