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| #include <iostream> #include <cstdio> #include <cstring> #include <vector> using namespace std; #define N 100010 #define INF 0x3f3f3f3f #define cl memset
int n,tot,head[N]; struct edge{ int v,next; }e[2*N]; int first[N],last[N],dcnt; int fa[N],depth[N]; int childen[N][2],des[N][2]; int bro[N]; int min1,min2,index1,index2; int ance[N];
inline void add(int u,int v){ e[tot].v = v; e[tot].next = head[u]; head[u] = tot++; }
inline void updata(int u,int v){ if(v < childen[u][0]){ childen[u][1] = childen[u][0]; childen[u][0] = v; } else if(v < childen[u][1]) childen[u][1] = v; int Min1,Min2; Min1 = min(v,des[v][0]); Min2 = (Min1 == v) ? des[v][0] : min(v,des[v][1]); if(Min1 < des[u][0]){ des[u][1] = des[u][0]; des[u][0] = Min1; } else if(Min1 < des[u][1]) des[u][1] = Min1; if(Min2 < des[u][1]) des[u][1] = Min2;
} void dfs(int u,int par,int dep,int __ance){ first[u] = ++dcnt; fa[u] = par; depth[u] = dep; if(dep == 2) ance[u] = u; else if(dep > 2) ance[u] = __ance; for(int k = head[u]; k != -1; k = e[k].next){ int v = e[k].v; if(v == par) continue; int temp = (dep == 2) ? u : __ance; dfs(v,u,dep+1,temp); updata(u,v); if(u == 1){ int Min = min(v,min(des[v][0],des[v][1])); if(Min < min1){ min2 = min1; index2 = index1; min1 = Min; index1 = v; } else if(Min < min2){ min2 = Min; index2 = v; } } } last[u] = ++dcnt; }
inline bool check(int u ,int v){ if(first[v] < first[u] && last[u] < last[v]) return false; return true; }
int main(){ int cas,q; scanf("%d",&cas); while(cas--){
scanf("%d%d",&n,&q); tot = dcnt = 0; min1 = min2 = INF; index1 = index2 = -1; cl(childen,0x3f,sizeof(childen)); cl(des,0x3f,sizeof(des)); cl(bro,0x3f,sizeof(bro)); cl(head,-1,sizeof(head)); for(int i = 1; i < n; i++){ int u,v; scanf("%d%d",&u,&v); add(u,v); add(v,u); }
dfs(1,INF,1,-1); for(int k = head[1]; k != -1; k = e[k].next){ int v = e[k].v; if(v != index1) bro[v] = min1; else bro[v] = min2; }
while(q--){ int u,v,res,__res; scanf("%d%d",&u,&v); if(check(u,v)){ res = childen[v][0]; __res = des[v][0]; if(res == INF) puts("no answers!"); else printf("%d %d\n",res,__res); } else{ if(childen[v][0] == u || !check(u,childen[v][0])) res = min(childen[v][1],fa[v]); else res = min(childen[v][0],fa[v]); if(res == INF){ puts("no answers!"); continue; } if(v != 1) __res = 1; else{ int ance1 = ance[des[1][0]]; int ance2 = ance[des[1][1]]; int ance3 = ance[u]; if(ance1 != ance3) __res = des[1][0]; else if(ance2 != ance3) __res = des[1][1]; else __res = bro[ance3]; } printf("%d %d\n",res,__res); } } puts(""); } return 0; }
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