Submission #76483

#	Time	Username	Problem	Language	Result	Execution time	Memory
76483		hamzqq9	Torrent (COI16_torrent)	C++14	0 / 100	1857 ms	21036 KiB

torrent

#include<bits/stdc++.h>
#define st first
#define nd second
#define pb push_back
#define ppb pop_back
#define umax(x,y) x=max(x,y)
#define umin(x,y) x=min(x,y)
#define ll long long
#define ii pair<int,int>
#define iii pair<ii,int>
#define iiii pair<ii,ii>
#define sz(x) ((int) x.size())
#define orta ((bas+son)>>1)
#define all(x) x.begin(),x.end()
#define dbgs(x) cerr<<(#x)<<" --> "<<(x)<<" "
#define dbg(x) cerr<<(#x)<<" --> "<<(x)<<endl;getchar()
#define pw(x) (1<<(x))
#define inf 60000000000000000
#define MOD 1000000009
#define N 300005
#define MAX 5032117	
#define LOG 30
#define KOK 333
using namespace std;

int tut,n,a,b,x,y;
vector<int> tr,alle,v[N];

int dfs(int node,int ata,bool state) {

	vector<int> ress;

	for(int to:v[node]) {

		if(to==ata || (!state && to==alle[tut+1]) || (state && to==alle[tut])) continue ;

		int res=dfs(to,node,state);

		ress.pb(res);

	}

	sort(all(ress),greater<int>());

	int ret=0;

	for(int i=0;i<sz(ress);i++) umax(ret,ress[i]+i+1);

	return ret;

}

int solve(int upto) {

	tut=upto;

	return max(dfs(a,0,0),dfs(b,0,1));

}

void process() {

	for(int i:tr) alle.pb(i);

}

void dfs1(int node,int ata) {

	tr.pb(node);

	if(node==b) {

		process();

		return ;

	} 

	for(int i:v[node]) {

		if(i==ata) continue ;

		dfs1(i,node);

	}

	tr.ppb();

}

int main() {

	//freopen("input.txt","r",stdin);

	scanf("%d %d %d",&n,&a,&b);

	for(int i=1;i<n;i++) {

		scanf("%d %d",&x,&y);

		v[x].pb(y);
		v[y].pb(x);

	}

	dfs1(a,0);

	int bas=0,son=sz(alle)-2;

	#define inf 100000000

	int ans=inf;

	while(bas+1<=son) {

		int res1=solve(orta);
		int res2=solve(orta+1);

		if(res1<res2) son=orta;
		else bas=orta+1;

	}

	bas=0,son=sz(alle)-2;

	while(bas+1<=son) {

		int res1=solve(orta);
		int res2=solve(orta+1);

		if(res1<=res2) son=orta;
		else bas=orta+1;

	}	

	umin(ans,solve(orta));

	printf("%d",ans);

}

Compilation message (stderr)

torrent.cpp:110:0: warning: "inf" redefined
  #define inf 100000000
 
torrent.cpp:18:0: note: this is the location of the previous definition
 #define inf 60000000000000000
 
torrent.cpp: In function 'int main()':
torrent.cpp:95:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d",&n,&a,&b);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~
torrent.cpp:99:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&x,&y);
   ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 31
• Subtask 2: 0 / 69