Submission #37726

#	Time	Username	Problem	Language	Result	Execution time	Memory
37726		Kerim	Hard route (IZhO17_road)	C++14	52 / 100	569 ms	5536 KiB

road

#include "bits/stdc++.h"
#define MAXN 100009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x)  cerr<< #x <<" = "<< x<<endl;
using namespace std;

typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
vector<int>adj[MAXN];
int ans,cnt,dp[MAXN],dp2[MAXN];
void precalc(int nd,int pr){
	dp[nd]=dp2[nd]=0;
	for(int i=0;i<int(adj[nd].size());i++){
		int to=adj[nd][i];
		if(to==pr)
			continue;
		precalc(to,nd);
		if(dp[nd]<dp[to]+1){
			dp2[nd]=dp[nd];
			dp[nd]=dp[to]+1;
		}
		else if(dp2[nd]<dp[to]+1)
			dp2[nd]=dp[to]+1;
	}
}
void dfs(int nd,int pr,int dis,int mx){
	if(~pr and (int)adj[nd].size()==1){
		if(dis*mx>ans){
			ans=dis*mx;
			cnt=1;
		}
		else if(dis*mx==ans)
			cnt++;
		return;	
	}
	for(int i=0;i<int(adj[nd].size());i++){
		int to=adj[nd][i];
		if(to==pr)
			continue;
		if(dp[to]+1==dp[nd])	
			dfs(to,nd,dis+1,max(dp2[nd],mx));
		else
			dfs(to,nd,dis+1,max(dp[nd],mx));
	}
}
int main(){
    //~ freopen("file.in", "r", stdin);
    int n;
    scanf("%d",&n);
    if(n==2){
		puts("0 1");
		return 0;
	}
    for(int i=1;i<n;i++){
		int u,v;
		scanf("%d%d",&u,&v);
		adj[u].pb(v);
		adj[v].pb(u);
	}
	for(int i=1;i<=n;i++)
		if(adj[i].size()==1){
			precalc(i,-1);
			dfs(i,-1,0,0);
		}
	printf("%d %d\n",ans,cnt/2);	
	return 0;
}

Compilation message (stderr)

road.cpp: In function 'int main()':
road.cpp:60:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
                   ^
road.cpp:67:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&u,&v);
                      ^

• Subtask 1: 19 / 19
• Subtask 2: 33 / 33
• Subtask 3: 0 / 48