1139C.cpp

1139C.cpp

@@ -0,0 +1,104 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+
+#define fast_cin() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
+#define MAX 1000000
+#define ll long long
+#define db double
+#define pb push_back
+#define For(i,s,e) for (ll i=(s); i<(e); i++)
+#define Debug_array(a,n) for (ll i=(0); i<(n); i++) cout<<a[i]<<" "
+#define Foe(i,s,e) for (ll i=(s); i<=(e); i++)
+#define Fod(i,s,e) for (ll i=(s)-1; i>=(e); i--)
+#define all(v) v.begin(),v.end()
+#define vll vector<ll>
+#define vs vector<string>
+
+#define mapll map<ll,ll>
+#define mapss map<string,string>
+#define mapsl map<string,ll>
+#define mapls map<ll,string>
+
+#define pll pair<ll,ll>
+#define pss pair<string,string>
+#define psl pair<ll,string>
+#define pls pair<string,ll>
+
+#define minheap priority_queue<ll>
+#define maxheap priority_queue<ll,vector<ll> ,greater<ll>>
+
+#define ff first
+#define ss second
+#define endl "\n"
+#define mp make_pair
+#define big_prime 15486277
+#define bigger_prime 179424697
+#define biggest_prime 32416188691
+const ll mod=1e9 + 7;
+
+
+ll takemod(ll a) {
+    return ((a%mod)+mod)%mod;
+}
+
+ll gcd(ll a, ll b) { 
+    if (b == 0) 
+        return a; 
+    return gcd(b, a % b);        
+}
+
+ll fast_exp(ll base, ll expo) {
+    ll res=1;
+    while(expo>0) {
+        if(expo&1) res=(res*base)%mod;
+        base=(base*base)%mod;
+        expo>>=1;}
+    return res;
+}
+
+ll modinv(ll a) {
+    return takemod(fast_exp(takemod(a), mod-2));
+}
+vector<pll> graph[100005];
+ll visited[100005];
+ll n,k,ans=0,finalans;
+void dfs(ll index)
+{
+    visited[index]=1;
+    ans++;
+    for(pll a: graph[index])
+    {
+        if(visited[a.ff]==-1 and a.ss==0)
+        {
+            dfs(a.ff);
+        }
+    }   
+}
+//unordered_map<ll,ll> umap1[100005];
+signed main() 
+{
+    fast_cin();
+    memset(visited,-1,sizeof(visited));
+    cin>>n>>k;
+    finalans=fast_exp(n,k);
+    For(i,0,n-1)
+    {
+        ll a,b,c;
+        cin>>a>>b>>c;
+        graph[a].pb(mp(b,c));
+        graph[b].pb(mp(a,c));
+    }
+    For(i,1,n+1)
+    {
+        if(visited[i]==-1)
+        {
+            dfs(i);
+            //cout<<ans<<endl;
+            finalans=((finalans-fast_exp(ans,k))+mod)%mod;
+            ans=0;
+        }
+    }
+    cout<<finalans<<endl;
+    return 0;    
+}