https://vjudge.net/problem/计蒜客-44317/origin

让最大值走得最多就好了,让最大值走最长链的长度,然后把最长链上的点都打上标记,再从所有没有被标记的点里找次长链,让次大值跑
这个题我最后一小时写慌了,思路乱了,队友写得很妙,tql

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(long long i=a;i<=b;++i)

using namespace std;
long long n,k,ans,cnt,f,x,s;
long long a[N],d[N],son[N];
bool vis[N];
struct tree{
    long long id;
    long long dep;
    bool operator < (const tree &x) const{
        return dep>x.dep;
    }
}b[N];

struct node{
    long long n;
    node *next;
}*e[N];

void in(long long &x){
    long long y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(long long x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

void push(long long x,long long y){
    node *p;
    p=new node();
    p->n=y;
    if(e[x]==0)
        e[x]=p;
    else{
        p->next=e[x]->next;
        e[x]->next=p;
    }
}

void dfs(long long x){
    b[x].dep=1;
    for(node *i=e[x];i;i=i->next){
        if(i->n!=d[x]){
            dfs(i->n);
            if(b[i->n].dep+1>b[x].dep){
                b[x].dep=b[i->n].dep+1;
                son[x]=i->n;
            }
        }
    }
}

bool cmp(long long x,long long y){
    return x>y;
}

signed main(){
    in(n);in(k);d[1]=1;
    For(i,1,k) in(a[i]);
    For(i,2,n){
        in(x);
        d[i]=++x;
        push(i,x);push(x,i);
    }
    For(i,1,n) b[i].id=i;
    dfs(1);
    sort(a+1,a+n+1,cmp);
    sort(b+1,b+n+1);
    b[1].dep--;
    For(i,1,n){
        if(!vis[b[i].id]){
            vis[b[i].id]=1;
            ans+=a[++cnt]*b[i].dep;
            s=son[b[i].id];
            while(s){
                vis[s]=1;
                s=son[s];
            }
        }
    }
    o(ans);
    return 0;
}

 

posted @ 2020-03-25 20:28  WeiAR  阅读(...)  评论(...编辑  收藏