Submit: 1077 Solved: 645
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Description
Input
Output
对于每个bridge命令与excursion命令,输出一行,为题目描述所示。
Sample Input
4 2 4 5 6
10
excursion 1 1
excursion 1 2
bridge 1 2
excursion 1 2
bridge 3 4
bridge 3 5
excursion 4 5
bridge 1 3
excursion 2 4
excursion 2 5
Sample Output
impossible
yes
6
yes
yes
15
yes
15
16
/************************************************************** Problem: 2843 User: JYYHH Language: C++ Result: Accepted Time:1584 ms Memory:2124 kb ****************************************************************/ #include<bits/stdc++.h> #define maxn 30005 using namespace std; int ch[maxn][2],a[maxn]; int tot[maxn],tag[maxn]; int q[maxn],tp,n,m,f[maxn]; char s[11]; inline int get(int x){ return ch[f[x]][1]==x; } inline int isroot(int x){ return (ch[f[x]][1]!=x&&ch[f[x]][0]!=x); } inline void update(int x){ tot[x]=a[x]+tot[ch[x][0]]+tot[ch[x][1]]; } inline void pushdown(int x){ if(tag[x]){ tag[x]=0,swap(ch[x][0],ch[x][1]); tag[ch[x][1]]^=1,tag[ch[x][0]]^=1; } } inline void rotate(int x){ int fa=f[x],ffa=f[fa],tp=get(x); ch[fa][tp]=ch[x][tp^1],f[ch[fa][tp]]=fa; ch[x][tp^1]=fa,f[fa]=x; f[x]=ffa; if(ch[ffa][1]==fa||ch[ffa][0]==fa) ch[ffa][ch[ffa][1]==fa]=x; update(fa),update(x); } inline void splay(int x){ for(int i=x;;i=f[i]){ q[++tp]=i; if(isroot(i)) break; } for(;tp;tp--) pushdown(q[tp]); for(;!isroot(x);rotate(x)) if(!isroot(f[x])) rotate(get(f[x])==get(x)?f[x]:x); } inline void access(int x){ for(int t=0;x;t=x,x=f[x]) splay(x),ch[x][1]=t,update(x); } inline void makeroot(int x){ access(x),splay(x),tag[x]^=1; } inline int froot(int x){ access(x),splay(x); while(ch[x][0]) x=ch[x][0]; return x; } inline int link(int x,int y){ makeroot(x),f[x]=y; } int main(){ int uu,vv; scanf("%d",&n); for(int i=1;i<=n;i++) scanf("%d",a+i); scanf("%d",&m); while(m--){ scanf("%s",s); if(s[0]=='b'){ scanf("%d%d",&uu,&vv); if(froot(uu)==froot(vv)) puts("no"); else link(uu,vv),puts("yes"); } else if(s[0]=='p'){ scanf("%d%d",&uu,&vv); splay(uu); a[uu]=vv,update(uu); } else{ scanf("%d%d",&uu,&vv); if(froot(uu)!=froot(vv)) puts("impossible"); else{ makeroot(vv),access(uu),splay(uu); printf("%d\n",tot[uu]); } } } return 0; }