#include<bits/stdc++.h> #define fgx cerr<<"-----------------------"<<endl using namespace std; #define LL long long #define DB double #define pb push_back #define pii pair<int,int> #define mpt make_pair #define fr first #define sc second #define M 100020//Size #define INF 1000000000 #define INFLL 1000000000000000000 inline int read(){ int nm=0,fh=1; char c=getchar(); for(;!isdigit(c);c=getchar()) if(c=='-') fh=-1; for(;isdigit(c);c=getchar()) nm=nm*10+c-'0'; return nm*fh; } #define mod 1000000007//About inline int add(int x,int y){return (x+y>=mod)?(x+y-mod):(x+y);} inline int mns(int x,int y){return (x-y<0)?(x-y+mod):(x-y);} inline int mul(LL x,LL y){return x*y%mod;} inline void upd(int &x,int y){x=(x+y>=mod)?(x+y-mod):(x+y);} inline void dec(int &x,int y){x=(x-y<0)?(x-y+mod):(x-y);} inline int qpow(int x,LL sq){int res=1;for(;sq;sq>>=1,x=mul(x,x))if(sq&1)res=mul(res,x);return res;} const int dx[]={0,1,0,-1},dy[]={1,0,-1,0}; class Solution { public: /** * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 * * @param n int整型 节点个数 * @param u int整型vector * @param v int整型vector * @return int整型 */ int to[M<<1],nt[M<<1],fs[M],tot; int F[M],G[M],H[M],n,mx; inline void link(int x,int y){to[++tot]=y,nt[tot]=fs[x],fs[x]=tot;} inline void dfs(int x,int last=0){ for(int i=fs[x],y;i;i=nt[i]) if((y=to[i])^last) dfs(y,x),mx=max(mx,F[y]+1+F[x]),F[x]=max(F[x],F[y]+1); } inline void dfs2(int x,int now,int last=0){ G[x]=now; int Mx=-(n<<1),Mx2=-(n<<1); for(int i=fs[x],y;i;i=nt[i]) if((y=to[i])^last){ int tmp=F[y]+1; if(tmp>Mx) Mx2=Mx,Mx=tmp; else if(tmp>Mx2) Mx2=tmp; } H[x]=Mx2; for(int i=fs[x],y;i;i=nt[i]) if((y=to[i])^last){ int tmp=(F[y]+1==Mx)?Mx2:Mx; dfs2(y,max(now,tmp)+1,x); } } int PointsOnDiameter(int N, vector<int>& u, vector<int>& v) { // write code here n=N; //fgx; mx=0; for(int i=0;i<n-1;i++) link(u[i],v[i]),link(v[i],u[i]); dfs(1); dfs2(1,0); int ans=0; //for(int i=1;i<=n;i++) // printf("%d %d %d\n",F[i],G[i],H[i]); for(int i=1;i<=n;i++){ int tmp=F[i]+max(G[i],H[i]); if(tmp==mx) ans++; } return ans; } }t;
全部评论
(9) 回帖