【Hash】bzoj4337 BJOI2015树的同构

来源：互联网发布：自动切换窗口软件编辑：程序博客网时间：2024/05/23 16:36

http://www.lydsy.com/JudgeOnline/problem.php?id=4337

树的哈希，模板题。

#include<bits/stdc++.h>#define fer(i,j,n) for(int i=j;i<=n;i++)#define far(i,j,n) for(int i=j;i>=n;i--)#define ll long long#define pa pair<int,int>const int maxn=1010;const int INF=1e9+7;using namespace std;/*----------------------------------------------------------------------------*/inline ll read(){    char ls;ll x=0,sng=1;    for(;ls<'0'||ls>'9';ls=getchar())if(ls=='-')sng=-1;    for(;ls>='0'&&ls<='9';ls=getchar())x=x*10+ls-'0';    return x*sng;}/*----------------------------------------------------------------------------*/struct kaga{    int next;    int point;}e[maxn];int m,n,ans[maxn][maxn],last[maxn],k=0,root,cnt=0;void add_edge(int x,int y){    e[++k].next=y;e[k].point=last[x];last[x]=k;}void insert(int x,int y){    add_edge(x,y);    add_edge(y,x);}map<int,int> l[maxn];map<vector<int>,int> h;int dfs(int x,int fa){    if(l[x][fa])return l[x][fa];    vector<int> now;    for(int j=last[x];j;j=e[j].point)    {        int y=e[j].next;        if(y!=fa)now.push_back(dfs(y,x));    }    sort(now.begin(),now.end());    if(!h[now])h[now]=++cnt;    return l[x][fa]=h[now];}bool judge(int i,int j){    fer(k,1,n)        if(ans[j][k]!=ans[i][k])return false;    return true;}int main(){    int m=read();    fer(i,1,m)    {        memset(last,0,sizeof(last));        k=0;        n=read();        fer(j,1,n)l[j].clear();        fer(j,1,n)        {            int x=read();            if(x)insert(x,j);        }        fer(j,1,n)            ans[i][j]=dfs(j,0);        sort(ans[i]+1,ans[i]+n+1);        fer(j,1,i)        if(judge(i,j))        {            cout<<j<<endl;            break;        }    }}

阅读全文

0 0