[uva] Add C++ solution for 11838 - Come and Go.

Author: abeaumont

uva/11838-1.ans

@@ -0,0 +1,4 @@
+1
+1
+0
+0

uva/11838-1.in

@@ -0,0 +1,16 @@
+4 5
+1 2 1
+1 3 2
+2 4 1
+3 4 1
+4 1 2
+3 2
+1 2 2
+1 3 2
+3 2
+1 2 2
+1 3 1
+4 2
+1 2 2
+3 4 2
+0 0

uva/11838.cc

@@ -0,0 +1,49 @@
+// https://uva.onlinejudge.org/external/118/11838.pdf
+#include<bits/stdc++.h>
+using namespace std;
+using vi=vector<int>;
+using si=unordered_set<int>;
+using vsi=vector<si>;
+int main(){
+  ios::sync_with_stdio(0);
+  cin.tie(0);
+  while(1){
+    int n,m,u,v,p;
+    cin>>n>>m;
+    if(!n)break;
+    vsi g(n),h(n);
+    for(int i=0;i<m;i++){
+      cin>>u>>v>>p;
+      u--;v--;
+      g[u].insert(v);
+      h[v].insert(u);
+      if(p==2){
+        g[v].insert(u);
+        h[u].insert(v);
+      }
+    }
+    vi s(n),t(n);
+    int k;
+    function<void(int)> dfs1=[&](int i){
+      s[i]=1;
+      for(int j:g[i])
+        if(!s[j])dfs1(j);
+      k=i;
+    };
+    for(int i=0;i<n;i++)
+      if(!s[i])dfs1(i);
+    function<void(int)> dfs2=[&](int i){
+      t[i]=1;
+      for(int j:h[i])
+        if(!t[j])dfs2(j);
+    };
+    dfs2(k);
+    int c=1;
+    for(int i=0;i<n;i++)
+      if(!t[i]){
+        c=0;
+        break;
+      }
+    cout<<c<<"\n";
+  }
+}

uva/README.md

@@ -21,3 +21,5 @@ There are solutions for the following
   ([contest site](http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=1055))
 * [11679 - Sub-prime](11679.cc)
   ([contest site](http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=2726))
+* [11838 - Come and Go](11838.cc)
+  ([contest site](https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=24&problem=2938))