Submission #9534456

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int Maxn=1005,Maxm=2005,mod=1e9+7;
bool chk[Maxm];
vector<pair<int,int>>w[Maxn];
struct node{int x,y,v;}e[Maxm];
int fa[Maxn];ll X;
int Getfa(int x){return fa[x]=(fa[x]==x?x:Getfa(fa[x]));}
int dfs(int x,int fa,int t){
    if(x==t)return -1;
    for(auto i:w[x]){
        int y,v;tie(y,v)=i;
        if(y==fa)continue;
        if(int ret=dfs(y,x,t))
            return max(ret,v);
    }
    return 0;
}
int ksm(int x,int k){
    int ret=1,tmp=x;
    while(k){
        if(k&1)ret=1ll*ret*tmp%mod;
        tmp=1ll*tmp*tmp%mod;k>>=1;
    }
    return ret;
}
int main(){
    int n,m;scanf("%d%d%lld",&n,&m,&X);
    for(int i=1;i<=n;i++)fa[i]=i;
    for(int i=1;i<=m;i++)
        scanf("%d%d%d",&e[i].x,&e[i].y,&e[i].v);
    sort(e+1,e+m+1,[](const node&a,const node&b){
        return a.v<b.v;
    });
    ll cost=0,cnt1=0,cnt2=0;
    for(int i=1;i<=m;i++){
        int x=e[i].x,y=e[i].y;
        if(Getfa(x)==Getfa(y))continue;
        fa[Getfa(x)]=Getfa(y);
        cost+=e[i].v;chk[i]=true;
        w[x].emplace_back(y,e[i].v);
        w[y].emplace_back(x,e[i].v);
    }
    if(cost>X){
        cout<<"0\n";
        return 0;
    }
    for(int i=1;i<=m;i++){
        if(chk[i])continue;
        int v=e[i].v-dfs(e[i].x,0,e[i].y);
        if(v==X-cost)cnt1++;
        if(v>X-cost)cnt2++;
    }
    int ans=1ll*ksm(2,cnt2+1)*(ksm(2,cnt1)-1);
    if(X==cost)ans=(ans+1ll*(ksm(2,n-1)-2)*ksm(2,m-n+1))%mod;
    cout<<(ans+mod)%mod<<"\n";
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:29:39: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     int n,m;scanf("%d%d%lld",&n,&m,&X);
                                       ^
./Main.cpp:32:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&e[i].x,&e[i].y,&e[i].v);
                                                ^

Judge Result