Submission #1692376

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Source Code Expand

#include<bits/stdc++.h>
#define ll long long
#define inf 1000000000
#define N 100009
using namespace std;

int n,rt,tot=1,fst[N],pnt[N<<1],len[N<<1],nxt[N<<1],sz[N]; ll ans;
void add(int x,int y,int z){
	pnt[++tot]=y; len[tot]=z; nxt[tot]=fst[x]; fst[x]=tot;
}
void dfs(int x,int p){
	int i,y,tmp=0; sz[x]=1;
	for (i=fst[x]; i; i=nxt[i]) if (i^p^1){
		y=pnt[i]; dfs(y,i);
		sz[x]+=sz[y]; tmp=max(tmp,sz[y]);
	}
	ans+=2ll*len[p]*min(sz[x],n-sz[x]);
	if (!rt && max(tmp,n-sz[x])<=(n>>1)) rt=x;
}
int main(){
	scanf("%d",&n);
	int i,x,y,z;
	for (i=1; i<n; i++){
		scanf("%d%d%d",&x,&y,&z);
		add(x,y,z); add(y,x,z);
	}
	dfs(1,0);
	ans=0; dfs(rt,0);
	for (i=fst[rt]; i; i=nxt[i]){
		x=pnt[i];
		if ((sz[x]<<1)==n) break;
	}
	if (i) ans-=len[i];
	else{
		for (i=fst[rt],x=inf; i; i=nxt[i]) x=min(x,len[i]);
		ans-=x;
	}
	printf("%lld\n",ans);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:21:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:24:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d",&x,&y,&z);
                           ^

Judge Result