QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#751536 | #9570. Binary Tree | Crying# | TL | 2ms | 6520kb | C++14 | 2.1kb | 2024-11-15 19:17:24 | 2024-11-15 19:17:24 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5+10,INF = 1e9;
int T,n,vis[N];
vector<int> e[N];
void link(int x,int y){e[x].push_back(y); e[y].push_back(x);}
int dep[N],x,y,dx[N],dy[N],sz[N],fa[N];
vector<int> o;
void dfs(int u){
if(!vis[u])return;
o.push_back(u);
sz[u] = 1;
for(auto v : e[u])if(v != fa[u]){
dep[v] = dep[u] + 1; fa[v] = u;
dfs(v);
sz[u] += sz[v];
}
}
int all;
int W(int x,int y){
if(fa[x] == y)return sz[x];
else return all - sz[y];
}
void solve(){
scanf("%d",&n); int num = 0;
for(int i=1;i<=n;i++)e[i].clear(),vis[i] = 1;
for(int i=1;i<=n;i++){
int x,y; scanf("%d%d",&x,&y);
if(x)link(i,x); if(y)link(i,y);
}
while(1){
int cnt = 0,ans = 0;
for(int i=1;i<=n;i++)if(vis[i])cnt++,ans = i;
if(cnt == 1){
printf("! %d\n",ans); fflush(stdout);
return;
}
x = y = 0; o.clear(); int rw = INF;
fa[ans] = 0; dfs(ans); all = sz[ans];
for(auto u : o){
for(auto v : e[u])if(vis[v]){
int w = max(W(u,v),W(v,u));
if(rw > w){
rw = w; x = u,y = v;
}
}
for(auto a : e[u])for(auto b : e[u])if(vis[a] && vis[b] && a!=b){
int w = max({W(a,u),W(b,u),all - W(a,u) - W(b,u)});
if(rw > w){
rw = w; x = a,y = b;
}
}
}
//
dep[x] = fa[x] = 0; dfs(x); for(int i=1;i<=n;i++)dx[i] = dep[i];
dep[y] = fa[y] = 0; dfs(y); for(int i=1;i<=n;i++)dy[i] = dep[i];
printf("? %d %d\n",x,y); fflush(stdout);
//exit(0);
int res; scanf("%d",&res);
for(int i=1;i<=n;i++)if(vis[i]){
if(res == 0)vis[i] = (dx[i] < dy[i]);
else if(res == 1)vis[i] = (dx[i] == dy[i]);
else vis[i] = (dx[i] > dy[i]);
}
}
}
int main(){
scanf("%d",&T);
while(T--)solve();
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 2ms
memory: 6520kb
input:
2 5 0 0 1 5 2 4 0 0 0 0 2 0 2 0 2 0 0 2
output:
? 1 3 ? 4 3 ! 4 ? 2 1 ! 1
result:
ok OK (2 test cases)
Test #2:
score: -100
Time Limit Exceeded
input:
5555 8 2 0 8 6 0 0 3 0 0 0 7 0 0 0 5 4 2 2 2 8 0 0 1 4 2 0 0 0 7 8 0 0 3 0 6 0 0 0 0
output:
? 8 2 ? 1 6 ? 7 6 ! 6 ? 7 3 ? 5 7 ? 8 5 ? 8 6