bzoj1149

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=1149

水题。。。。。

直接BFS。

#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<fstream>

#include<algorithm>

#include<cstring>

#include<string>

#include<cmath>

#include<queue>

#include<stack>

#include<map>

#include<utility>

#include<set>

#include<bitset>

#include<vector>

#include<functional>

#include<deque>

#include<cctype>

#include<climits>

#include<complex>

//#include<bits/stdc++.h>适用于CF,UOJ，但不适用于poj

using namespace std;

typedef long long LL;

typedef double DB;

typedef pair<int,int> PII;

typedef complex<DB> CP;

#define mmst(a,v) memset(a,v,sizeof(a))

#define mmcy(a,b) memcpy(a,b,sizeof(a))

#define re(i,a,b)  for(i=a;i<=b;i++)

#define red(i,a,b) for(i=a;i>=b;i--)

#define fi first

#define se second

#define m_p(a,b) make_pair(a,b)

#define SF scanf

#define PF printf

#define two(k) (1<<(k))

template<class T>inline T sqr(T x){return x*x;}

template<class T>inline void upmin(T &t,T tmp){if(t>tmp)t=tmp;}

template<class T>inline void upmax(T &t,T tmp){if(t<tmp)t=tmp;}

const DB EPS=1e-;

inline int sgn(DB x){if(abs(x)<EPS)return ;return(x>)?:-;}

const DB Pi=acos(-1.0);

inline int gint()

  {

        int res=;bool neg=;char z;

        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());

        if(z==EOF)return ;

        if(z=='-'){neg=;z=getchar();}

        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());

        return (neg)?-res:res;

    }

inline LL gll()

  {

      LL res=;bool neg=;char z;

        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());

        if(z==EOF)return ;

        if(z=='-'){neg=;z=getchar();}

        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());

        return (neg)?-res:res;

  }

const int maxN=;

int N;

PII a[maxN+];

int maxdep,dep[maxN+];

int ans;

int head,tail,que[maxN+];

int cnt,val[*maxN+],sum[*maxN+];

int main()

  {

      freopen("bzoj1149.in","r",stdin);

      freopen("bzoj1149.out","w",stdout);

      int i;

      N=gint();

      dep[]=;

      re(i,,N)

        {

            a[i].fi=gint(),a[i].se=gint();

            if(a[i].fi!=-)dep[a[i].fi]=dep[i]+;

            if(a[i].se!=-)dep[a[i].se]=dep[i]+;

        }

        ans=;

        re(i,,N)upmax(maxdep,dep[i]);

      re(i,,N)if(a[i].fi==- || a[i].se==-)if(maxdep-dep[i]>){ans=-;break;}

      if(ans==-){cout<<ans<<endl;return ;}

      que[head=tail=]=;

      re(i,,maxdep-)

        {

            int temp=tail;

            while(head<=temp)

              {

                  int u=que[head++];

                  que[++tail]=a[u].fi;

                  que[++tail]=a[u].se;

              }

        }

      re(i,head,tail)

        {

            int u=que[i];

            val[++cnt]=(a[u].fi==-)?:;

            val[++cnt]=(a[u].se==-)?:;

        }

      re(i,,N)sum[i]=sum[i-]+val[i];

      int l=,r=cnt;

      while(l<r)

        {

            int mid=(l+r)/;

            int lf,rf;

            if(sum[mid]-sum[l-]==mid-l+) lf=; else if(sum[mid]-sum[l-]==) lf=; else lf=;

            if(sum[r]-sum[mid]==r-mid) rf=; else if(sum[r]-sum[mid]==) rf=; else rf=;

            if(lf== && rf==) {ans=-;break;}

            if(lf== && rf==) break;

            if(lf== && rf==) {ans++;break;}

            if(lf== && rf==) break;

            if(lf== && rf==) break;

            if(lf== && rf==) {ans++;l=mid+;continue;}

            if(lf== && rf==) {l=mid+;continue;}

            if(lf== && rf==) {r=mid;continue;}

            if(lf== && rf==) {ans++;r=mid;continue;}

        }

      cout<<ans<<endl;

      return ;

  }