Submission #1986081

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Source Code Expand

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#define ele int
using namespace std;
#define maxn 200010
const ele INF=1e9;
struct edge{
	ele v;
	edge *nxt;
}ep[maxn<<1],*ecnt;
ele n,r,d[maxn],f[maxn];
edge *h[maxn];
inline void addedge(ele u,ele v){
	edge *p=ecnt++;
	p->v=v; p->nxt=h[u];
	h[u]=p;
}
void dfs(ele p,ele i,ele B){
	vector<ele> lst;
	for (edge *j=h[i]; j; j=j->nxt)
		if (j->v!=p){
			dfs(i,j->v,B);
			lst.push_back(f[j->v]);
		}
	if (lst.size()%2==0) lst.push_back(0);
	sort(lst.begin(),lst.end());
	f[i]=INF;
	for (int r=0; r<lst.size(); ++r){
		ele u=0,v=lst.size()-1;
		bool flag=true;
		while (u<v){
			if (u==r) ++u;
			if (v==r) --v;
			if (u<v && lst[u]+lst[v]>B){ flag=false; break; }
			++u; --v;
		}
		if (flag){ f[i]=lst[r]+1; break; }
	}
}
inline bool test(ele B){
	dfs(-1,r,B);
	return f[r]<=B+1;
}
int main(){
	scanf("%d",&n);
	ecnt=ep; memset(h,0,sizeof(h)); memset(d,0,sizeof(d));
	for (int i=0; i<n-1; ++i){
		ele x,y;
		scanf("%d%d",&x,&y); --x,--y;
		addedge(x,y); addedge(y,x);
		++d[x]; ++d[y];
	}
	ele cnt=0;
	for (int i=0; i<n; ++i)
		if (d[i]&1) ++cnt,r=i;
	ele L=0,R=n-1;
	while (R-L>1){
		ele mid=(L+R)>>1;
		if (test(mid)) R=mid; else L=mid;
	}
	printf("%d %d\n",cnt/2,R);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:47:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:51:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x,&y); --x,--y;
                      ^

Judge Result