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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const long long MaxN = 1e6;
  5.  
  6. long long n;
  7. vector<long long> a[MaxN+5];
  8. bool visited[MaxN+5];
  9. long long depth[MaxN+5],color[MaxN+5];
  10. string s;
  11.  
  12. void input()
  13. {
  14.     cin >> n >> s;
  15.  
  16.     s=" "+s;
  17.  
  18.     for(long long i=1;i<=n;i++)
  19.     {
  20.         if(s[i]=='1')
  21.         {
  22.             color[i]=-1;
  23.         }
  24.         else
  25.         {
  26.             color[i]=1;
  27.         }
  28.     }
  29.  
  30.     for(long long i=1;i<=n-1;i++)
  31.     {
  32.         long long u,v;
  33.         cin >> u >> v;
  34.         a[u].push_back(v);
  35.         a[v].push_back(u);
  36.     }
  37. }
  38.  
  39. void dfs(long long i,vector<long long> a[],bool visited[],long long depth[],long long color[])
  40. {
  41.     stack<long long> st;
  42.  
  43.     st.push(i);
  44.     visited[i]=true;
  45.     depth[i]=color[i];
  46.  
  47.     while(!st.empty())
  48.     {
  49.         long long u=st.top();
  50.         st.pop();
  51.  
  52.         for(long long v:a[u])
  53.         {
  54.             if(!visited[v])
  55.             {
  56.                 visited[v]=true;
  57.                 depth[v]=depth[u]+color[v];
  58.                 st.push(v);
  59.             }
  60.         }
  61.     }
  62. }
  63.  
  64. void solve()
  65. {
  66.     memset(visited,false,sizeof(visited));
  67.     memset(depth,0,sizeof(depth));
  68.  
  69.     dfs(1,a,visited,depth,color);
  70.  
  71.     long long res=0;
  72.  
  73.     for(long long i=1;i<=n;i++)
  74.     {
  75.         if(depth[i]>0)
  76.         {
  77.             res++;
  78.         }
  79.     }
  80.  
  81.     cout << res;
  82. }
  83.  
  84. int main()
  85. {
  86.     ios_base::sync_with_stdio(0);
  87.     cin.tie(0);
  88.  
  89.     input();
  90.     solve();
  91. }
Success #stdin #stdout 0.01s 37032KB
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https://ideone.com/OTHzXn
language:
C++14 (gcc 8.3)
created:
7 hours ago
visibility:
public

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