update

src/11/25/U86017.cpp

@@ -0,0 +1,105 @@
+#include <algorithm>
+#include <cstdint>
+#include <functional>
+#include <ios>
+#include <iostream>
+#include <map>
+#include <ostream>
+#include <utility>
+
+using namespace std;
+using ll = int64_t;
+
+template<class T,class P>
+ostream&operator<<(ostream&os,map<T,P>const&m){
+    os<<"map { ";
+    for(auto [k,v]:m){
+        os<<"{ "<<k<<", "<<v<<" }, ";
+    }
+    os<<"}";
+    return os;
+}
+template<class T,class P>
+ostream&operator<<(ostream&os,pair<T,P>const&m){
+    os<<"pair { "<<m.first<<", "<<m.second<<" }";
+    return os;
+}
+
+
+ll const maxn{ll(1e5+5)};
+ll t,n,m,inf{ll(1)<<60};
+ll q[maxn],qs{};
+pair<ll, ll>e[maxn];
+
+struct DSU{
+    ll f[maxn];
+    DSU(){for(ll i{1};i<=n;i++){f[i]=i;}}
+    ll find(ll const&n){if(f[n]==n)return n; return f[n]=find(f[n]);}
+    bool merge(ll const&a,ll const&b){if(find(a)==find(b))return false;f[find(a)]=find(b);return true;}
+    friend ostream&operator<<(ostream&os,DSU const& d){
+        os<<"DSU { ";
+        for(ll i{1};i<=n;i++)os<<d.f[i]<<", ";
+        os<<"}";
+        return os;
+    }
+};
+char dmem[sizeof(DSU)+1024];
+DSU &dsu = *(DSU*)dmem;
+ll un[maxn];
+
+int main(){
+    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
+
+    cin>>t;
+    while(t--){
+        cin>>n>>m;
+        // cout<<n<<" "<<m<<'\n';
+        for(ll i{1};i<=m;i++){
+            ll u,v;
+            cin>>u>>v;
+            if(u>v)swap(u,v);
+            // cout<<"uv "<<u<<' '<<v<<'\n';
+            e[i].first=u,e[i].second=v;
+        }
+        sort(e+1,e+1+m,greater());
+        new(dmem) DSU();
+        // cout<<dsu<<'\n';
+        ll uns{};
+        for(ll i{1};i<=m;i++){
+            // cout<<e[i]<<'\n';
+            if(!dsu.merge(e[i].first, e[i].second)){
+                un[++uns]=i;
+            }
+        }
+        // cout<<dsu<<'\n';
+        map<ll, ll> mm;
+        for(ll i{1};i<=n;i++){
+            mm[dsu.find(i)] = min(mm[dsu.find(i)]==0?inf:mm[dsu.find(i)],i);
+        }
+        // cout<<mm<<' '<<uns<<' '<<un[uns]<<' '<<e[un[uns]]<<'\n';
+        // cout<<mm.size()<<' '<<uns<<'\n';
+        if((ll)mm.size()-1>uns&&mm.size()!=1){
+            cout<<"-1"<<'\n';
+            continue;
+        }
+        if(mm.size()==1){
+            cout<<"0\n";
+            continue;
+        }
+
+        qs=0;
+        for(auto const[k,v]:mm){
+            q[++qs]=v;
+        }
+        sort(q+1,q+1+qs);
+        // cout<<mm<<'\n';
+        // for(ll i{1};i<=qs;i++)cout<<q[i]<<" ,";
+        // cout<<'\n';
+        // cout<<mm<<'\n';
+        cout<<mm.size()-1<<'\n';
+        for(ll i{2};i<=qs;i++){
+            cout<<e[un[uns]].first<<" "<<e[un[uns-1]].second<<" "<<q[1]<<" "<<q[i]<<'\n';
+            --uns;
+        }
+    }
+}

src/11/25/rebuild/rebuild1.ans

@@ -0,0 +1,3 @@
+1
+2 5 1 2
+0

src/11/25/rebuild/rebuild1.in

@@ -0,0 +1,9 @@
+2
+5 5
+1 3
+3 4
+5 2
+5 2
+2 5
+2 1
+1 2

src/11/25/rebuild/rebuild2.ans

@@ -0,0 +1,5 @@
+0
+-1
+2
+1 2 1 5
+1 3 1 6

src/11/25/rebuild/rebuild2.in

@@ -0,0 +1,19 @@
+3
+5 4
+1 3
+3 4
+5 2
+1 2
+5 3
+1 3
+3 4
+5 2
+7 8
+1 2
+2 3
+3 1
+1 4
+2 4
+4 3
+6 7
+7 6

src/11/25/rebuild/rebuild3.ans

@@ -0,0 +1,16 @@
+2
+1 2 1 7
+1 5 1 8
+1
+3 7 1 2
+4
+1 5 1 2
+1 6 1 3
+1 6 1 4
+1 7 1 8
+3
+1 4 1 6
+1 9 1 7
+1 9 1 10
+1
+3 9 1 10

src/11/25/rebuild/rebuild3.in

@@ -0,0 +1,56 @@
+5
+10 10
+1 10
+2 1
+2 5
+1 6
+9 1
+5 9
+1 6
+1 4
+1 5
+1 3
+10 10
+3 9
+3 7
+5 10
+8 6
+6 1
+4 10
+7 9
+9 1
+3 5
+3 9
+10 10
+1 7
+1 6
+3 10
+9 1
+1 5
+1 5
+6 7
+1 6
+1 7
+9 1
+10 10
+9 2
+3 5
+5 8
+1 4
+9 1
+9 1
+1 9
+1 4
+9 1
+1 5
+10 10
+8 1
+3 1
+9 3
+2 4
+7 3
+3 9
+9 3
+2 3
+5 3
+6 5