[JLOI2014]松鼠的新家题解

来源：互联网发布：决战武林进阶数据亲编辑：程序博客网时间：2024/04/19 00:51

题目：https://www.luogu.org/problem/show?pid=3258

题解

此题与USACO Max Flow几乎是一样的（代码也几乎一样）。细节就自己想吧。

代码

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;int n;int toq[600100],nxtq[600100],headq[300100],totq;int top[600100],nxtp[600100],headp[300100],totp;int tmpfa[300100],fa[300100],record[300100],map[300100];bool vis[300100];void addq(int f,int t){    toq[++totq] = t;    nxtq[totq] = headq[f];    headq[f] = totq;}void addp(int f,int t){    top[++totp] = t;    nxtp[totp] = headp[f];    headp[f] = totp;}int find(int x){    if(tmpfa[x] == x)return x;    return tmpfa[x] = find(tmpfa[x]);}void tarjan(int pos,int pre){    tmpfa[pos] = pos;    for(int i = headp[pos];i;i = nxtp[i])        if(top[i] != pre){            tarjan(top[i],pos);            tmpfa[top[i]] = pos;        }    vis[pos] = true;    for(int i = headq[pos];i;i = nxtq[i])        if(vis[toq[i]]){            int tmp_lca = find(toq[i]);            record[tmp_lca]--,record[fa[tmp_lca]]--,record[pos]++,record[toq[i]]++;        }}void dfs(int pos,int pre){    fa[pos] = pre;    for(int i = headp[pos];i;i = nxtp[i])        if(top[i] != pre)            dfs(top[i],pos);}void dfsans(int pos,int pre){    for(int i = headp[pos];i;i = nxtp[i])        if(top[i] != pre){            dfsans(top[i],pos);            record[pos] += record[top[i]];        }}int main(){    scanf("%d",&n);    int f,t,ori;    scanf("%d",&f);ori = f;    for(int i = 1;i <  n;i++){        scanf("%d",&t);        map[t] = -1;        addq(f,t),addq(t,f);        f = t;    }    for(int i = 1;i <  n;i++){        scanf("%d%d",&f,&t);        addp(f,t),addp(t,f);    }    dfs(1,0);    tarjan(1,0);    dfsans(1,0);    for(int i = 1;i <= n;i++){        if(i == ori)            printf("%d\n",record[i]);        else            printf("%d\n",record[i] - 1);    }}

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