Submission #2489274

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Source Code Expand

#define DEB
#include<bits/stdc++.h>
#define REP(i,m) for(int i=0;i<(m);++i)
#define REPN(i,m,in) for(int i=(in);i<(m);++i)
#define ALL(t) (t).begin(),(t).end()
#define CLR(a) memset((a),0,sizeof(a))
#define pb push_back
#define mp make_pair
#define fr first
#define sc second

using namespace std;


#ifdef DEB
#define dump(x)  cerr << #x << " = " << (x) << endl
#define prl cerr<<"called:"<< __LINE__<<endl
template<class T> void 
debug(T a,T b){ for(;a!=b;++a) cerr<<*a<<' ';cerr<<endl;}
#else
#define dump(x) ;
#define prl ;
template<class T> void debug(T a,T b){ ;}
#endif

template<class T> void chmin(T& a,const T& b) { if(a>b) a=b; }
template<class T> void chmax(T& a,const T& b) { if(a<b) a=b; }

typedef long long int lint;
typedef pair<int,int> pi;

namespace std{
  template<class S,class T>
  ostream &operator <<(ostream& out,const pair<S,T>& a){
    out<<'('<<a.fr<<','<<a.sc<<')';
    return out;
  }
}

//const int INF=5e8;
int n;
vector<int> g[100005];
int col[100005];

bool mark[100005];


int dfs(int v,int p){
  int res=col[v];
  for(auto to:g[v]){
    if(to==p) continue;
    res+=dfs(to,v);
  }
  mark[v]=(res>0);
  return res;
}
int sign[100005];


int ans;
int dfs2(int v,int p){
  int res=0;
  for(auto to:g[v]) if(to!=p && mark[to]){
    int nxt=dfs2(to,v);
    chmax(ans,nxt+res+sign[v]);
    chmax(res,nxt);
  }
  res+=sign[v];
  return res;
}
int main(){
  cin>>n;
  REP(i,n-1){
    int a,b;cin>>a>>b;--a;--b;
    g[a].pb(b);
    g[b].pb(a);
  }
  char tmp[100005];
  scanf("%s",tmp);
  REP(i,n) col[i]=(tmp[i]=='W'?1:0);
  int R=-1;
  REP(i,n) if(col[i]) R=i;
  debug(col,col+n);
  dump(R);
  if(R==-1){
    puts("0");
    return 0;
  }
  dfs(R,-1);

  int tot=0;
  int add=0;
  REP(i,n) if(mark[i]){
    sign[i]=col[i];
    for(auto to:g[i]) if(mark[to]) sign[i]^=1,++tot;
    if(sign[i]) ++add;
  }
  debug(mark,mark+n);
  debug(sign,sign+n);

  dfs2(R,-1);
  dump(tot);dump(ans);dump(add);

  cout<<tot-ans*2+add<<endl;
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:79:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s",tmp);
                  ^

Judge Result