Submission #3466443

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Source Code Expand

#include <bits/stdc++.h>
                                        #include<iostream>
                                        #include<cstdio>
                                        #include<vector>
                                        #include<queue>
                                        #include<map>
                                        #include<cstring>
                                        #include<string>
                                        #include <math.h>
                                        #include<algorithm>
                                    //    #include <boost/multiprecision/cpp_int.hpp>
                                        #include<functional>
                               #define int long long
                                        #define inf  1000000007
                                        #define pa pair<int,int>
                                        #define ll long long
                                        #define pal pair<double,double>
                                        #define ppap pair<pa,int>
                                   
                                        #define ssa pair<string,int>
                                        #define  mp make_pair
                                        #define  pb push_back
                                        #define EPS (1e-10)
                                        #define equals(a,b) (fabs((a)-(b))<EPS)
int dx[4]={0,-1,0,1};
int dy[4]={1,0,-1,0};
                                        using namespace std;
                                        class pa3{
                                            public:
                                            int x,y,z;
                                            pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                            bool operator < (const pa3 &p) const{
                                                if(x!=p.x) return x<p.x;
                                                if(y!=p.y) return y<p.y;
                                                 return z<p.z;
                                                //return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator > (const pa3 &p) const{
                                                if(x!=p.x) return x>p.x;
                                                if(y!=p.y) return y>p.y;
                                                 return z>p.z;
                                                //return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator == (const pa3 &p) const{
                                                return x==p.x && y==p.y && z==p.z;
                                            }
                                                bool operator != (const pa3 &p) const{
                                                    return !( x==p.x && y==p.y && z==p.z);
                                            }
                                         
                                        };
                                         
                                        class pa4{
                                            public:
                                            double x;
                                            int y,z,w;
                                            pa4(double x=0,int y=0,int z=0,int w=0):x(x),y(y),z(z),w(w) {}
                                            bool operator < (const pa4 &p) const{
                                                if(x!=p.x) return x<p.x;
                                                if(y!=p.y) return y<p.y;
                                                if(z!=p.z)return z<p.z;
                                                return w<p.w;
                                                //return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator > (const pa4 &p) const{
                                                if(x!=p.x) return x>p.x;
                                                if(y!=p.y) return y>p.y;
                                                if(z!=p.z)return z>p.z;
                                                return w>p.w;
                                                //return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator == (const pa4 &p) const{
                                                return x==p.x && y==p.y && z==p.z &&w==p.w;
                                            }
                                                 
                                         
                                        };
                                        class pa2{
                                            public:
                                            int x,y;
                                            pa2(int x=0,int y=0):x(x),y(y) {}
                                            pa2 operator + (pa2 p) {return pa2(x+p.x,y+p.y);}
                                            pa2 operator - (pa2 p) {return pa2(x-p.x,y-p.y);}
                                            bool operator < (const pa2 &p) const{
                                                return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator > (const pa2 &p) const{
                                                return x != p.x ? x>p.x: y>p.y;
                                            }
                                            bool operator == (const pa2 &p) const{
                                                return abs(x-p.x)==0 && abs(y-p.y)==0;
                                            }
                                            bool operator != (const pa2 &p) const{
                                                return !(abs(x-p.x)==0 && abs(y-p.y)==0);
                                            }
                                                 
                                         
                                        };
                                         
                                               #define ppa pair<int,pas>
                                        class Point{
                                            public:
                                            double x,y;
                                            Point(double x=0,double y=0):x(x),y(y) {}
                                            Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                            Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                            Point operator * (double a) {return Point(x*a,y*a);}
                                            Point operator / (double a) {return Point(x/a,y/a);}
                                            double absv() {return sqrt(norm());}
                                            double norm() {return x*x+y*y;}
                                            bool operator < (const Point &p) const{
                                                return x != p.x ? x<p.x: y<p.y;
                                            }
                                            bool operator == (const Point &p) const{
                                                return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                            }
                                        };
                                        typedef Point Vector;
                                 #define pl pair<int,pas>
                                        struct Segment{
                                        Point p1,p2;
                                        };
                                         double dot(Vector a,Vector b){
                                            return a.x*b.x+a.y*b.y;
                                        }
                                        double cross(Vector a,Vector b){
                                            return a.x*b.y-a.y*b.x;
                                        }
                                     
            bool parareru(Point a,Point b,Point c,Point d){
            //  if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
                return abs(cross(a-b,d-c))<EPS;
            }
            double distance_ls_p(Point a, Point b, Point c) {
              if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
              if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
              return abs(cross(b-a, c-a)) / (b-a).absv();
            }
            bool is_intersected_ls(Segment a,Segment b) {
                if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
                if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
            //      cout<<"sss"<<endl;
                    if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
                    if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
                    if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
                    if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
                    return false;
                }
              else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
            }
              
            double segment_dis(Segment a,Segment b){
                if(is_intersected_ls(a,b))return 0;
                double r=distance_ls_p(a.p1, a.p2, b.p1);
                r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
                r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
                r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
                return r;
            }
            Point intersection_ls(Segment a, Segment b) {
              Point ba = b.p2-b.p1;
              double d1 = abs(cross(ba, a.p1-b.p1));
              double d2 = abs(cross(ba, a.p2-b.p1));
              double t = d1 / (d1 + d2);
              
              return a.p1 + (a.p2-a.p1) * t;
            }
              
                            string itos( int i ) {
                            ostringstream s ;
                            s << i ;
                            return s.str() ;
                            }
                              
                            int gcd(int v,int b){
                                if(v>b) return gcd(b,v);
                                if(v==b) return b;
                                if(b%v==0) return v;
                                return gcd(v,b%v);
                            }
              
                            double distans(double x1,double y1,double x2,double y2){
                                double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                                return sqrt(rr);
                                 
                            }
                             
   //         int pr[2000010];
     //       int inv[2000010];
             
            int beki(int wa,int rr,int warukazu){
                if(rr==0) return 1ll;
                if(rr==1) return wa%warukazu;
                if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
                int zx=beki(wa,rr/2,warukazu);
                return (zx*zx)%warukazu;
            }
            /*
            int comb(int nn,int rr){
                int r=pr[nn]*inv[rr];
                r%=inf;
                r*=inv[nn-rr];
                r%=inf;
                return r;
            }
             
            void gya(int ert){
                pr[0]=1;
                for(int i=1;i<ert;i++){
                    pr[i]=(pr[i-1]*i)%inf;
                }
                for(int i=0;i<ert;i++) inv[i]=beki(pr[i],inf-2,inf);
                 
            }
             */
            //priority_queue<pa3,vector<pa3>,greater<pa3>> pq;            
             //sort(ve.begin(),ve.end(),greater<int>());
                                     //----------------kokomade tenpure------------
            //vector<double> ans(100000000),ans2(100000000);
 
vector<int> G[100030];
int lc[100030][20];
int dep[100030];
 
void dfs(int r,int d){
    dep[r]=d;
     
    for(auto v:G[r]) dfs(v,d+1);
}
int lca(int a,int b){
    if(dep[a]<dep[b])swap(a,b);
     
    int sa=dep[a]-dep[b];
    int w=0;
    while(sa>0){
        if(sa&(1<<w)){
        a=lc[a][w];
            sa-=(1<<w);
        }
    w++;
    }
     
    if(a==b) return a;
     
     
    w=19;
     
    while(1){
        if(lc[a][w]==lc[b][w]){
            //w--;
        }
        else{
            a=lc[a][w];
            b=lc[b][w];
             
        }
        w--;
        if(w<0) break;
    }
     
    return lc[a][0];
}
 
queue<int> qu;
vector<int>ve;
   signed main(){
 
    int n;
   cin>>n;
     
    for(int i=2;i<=n;i++){
        int y;
    cin>>y;
         
        G[y].pb(i);
        lc[i][0]=y;
    }
    lc[1][0]=1;
     
    for(int d=1;d<20;d++){
        for(int i=1;i<=n;i++){
            lc[i][d]=lc[lc[i][d-1]][d-1];
         
        }
     
    }
     
    dfs(1,0);
    
    qu.push(1);
     
    while(qu.size()>0){
         
        int r=  qu.front();
        qu.pop();
        ve.pb(r);
         
        for(auto v:G[r])qu.push(v);
    }
         
    int ans=0;
    for(int i=0;i<n-1;i++){
         
        ans+=dep[ve[i]]+dep[ve[i+1]]-2*dep[lca(ve[i],ve[i+1])];
   //       cout<<ans<<endl;
    }
    cout<<ans<<endl;
    return 0;
        }

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