猴子
https://www.luogu.org/problemnew/show/P1653
題解:逆序并查集+DFS
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int using namespace std; typedef long long ll; //typedef __int128 lll; const int N=400000+10; const int M=100000+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,q; int ans[N],cnt,flag,temp,sum; int a[N][2]; bool b[N][2]; int c[N][2]; int vis[N]; vector<int>G[N]; char str; struct node{}; int pre[N]; int find(int x){return (pre[x]==x)?x:pre[x]=find(pre[x]);} void add(int x,int y){} void dfs(int u,int time){vis[u]=1;ans[u]=time;for(int i=0,j=G[u].size();i<j;i++){int v=G[u][i];if(vis[v]==0){vis[v]=1;dfs(v,time);vis[v]=0;}}vis[u]=0; } int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endif//ios::sync_with_stdio(false);//cin.tie(0);//cout.tie(0);//scanf("%d",&t);//while(t--){scanf("%d%d",&n,&m);for(int i=1;i<=n;i++){pre[i]=i;}for(int i=1;i<=n;i++){scanf("%d%d",&a[i][0],&a[i][1]);}for(int i=1;i<=m;i++){scanf("%d%d",&c[i][0],&c[i][1]);b[c[i][0]][c[i][1]-1]=1;}memset(ans,-1,sizeof(ans));for(int i=1;i<=n;i++){for(int j=0;j<=1;j++){if(!b[i][j]&&a[i][j]!=-1){int tx=find(i);int ty=find(a[i][j]);if(tx!=ty){if(tx==1){pre[ty]=tx;G[tx].push_back(ty);}else if(ty==1){pre[tx]=ty;G[ty].push_back(tx);}else{pre[tx]=ty;G[tx].push_back(ty);G[ty].push_back(tx);}}}}}vis[1]=1;for(int i=m;i>=1;i--){int u=c[i][0];int v=a[c[i][0]][c[i][1]-1];int tx=find(u);int ty=find(v);if(tx!=ty){if(tx==1){pre[ty]=tx;G[tx].push_back(ty);dfs(ty,i-1);}else if(ty==1){pre[tx]=ty;G[ty].push_back(tx);dfs(tx,i-1);}else{G[tx].push_back(ty);G[ty].push_back(tx);pre[tx]=ty;}}}for(int i=1;i<=n;i++){printf("%d\n",ans[i]);}//}#ifdef DEBUGprintf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC); #endif//cout << "Hello world!" << endl;return 0; }?
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