Submission #1825050

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Source Code Expand

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <utility>
#define FR first
#define SE second
#define last last2
 
using namespace std;
 
typedef long long ll;
 
typedef pair<ll,ll> pr;
 
vector <pr> a[1<<18];
pr p[1<<18],q[1<<18];
 
int ch[1<<18][2];
ll v[1<<18],d[1<<18];
 
void dfs(int x,int dep) {
  a[x].clear();
  int ls=ch[x][0],rs=ch[x][1];
  if (ls) {
    d[ls]=d[x]+v[ls];d[rs]=d[x]+v[rs];
    dfs(ls,dep);
    dfs(rs,dep);
    int s1=0,s2=0;
    if (a[rs].size()) {
    int r=0;
    for(int i=0;i<a[ls].size();i++) {
        while (r<a[rs].size()-1&&a[rs][r+1].FR+a[ls][i].SE-2*d[x]<=dep) r++;
        if (a[rs][r].FR+a[ls][i].SE-2*d[x]<=dep) p[++s1]=pr(a[ls][i].FR,a[rs][r].SE); 
      }
    }
    if (a[ls].size()) {
    int r=0;
    for(int i=0;i<a[rs].size();i++) {
        while (r<a[ls].size()-1&&a[ls][r+1].FR+a[rs][i].SE-2*d[x]<=dep) r++;
        if (a[ls][r].FR+a[rs][i].SE-2*d[x]<=dep) q[++s2]=pr(a[rs][i].FR,a[ls][r].SE); 
    }
    }
    int l=1,r=1;
    ll last=(ll)(1e17);
    for(int i=1;i<=s1+s2;i++)
      if (l<=s1&&(r>s2||p[l]<q[r])) {
        if (p[l].SE<last) {
          a[x].push_back(p[l]);
          last=p[l].SE;
        }
        l++;
      }
      else {
        if (q[r].SE<last) {
            a[x].push_back(q[r]);
            last=q[r].SE;
          }
        r++;
      }
  }
  else a[x].push_back(pr(d[x],d[x]));
}
 
int main() {
  int n;
  scanf("%d",&n);
  for(int i=2;i<=n;i++) {
    int x,y;
    scanf("%d%d",&x,&y);
    if (!ch[x][0]) ch[x][0]=i; else ch[x][1]=i;
    v[i]=y;
  }
  int l=0,r=1<<30;
  while (l<r) {
    int m=((l+r)>>1);
    dfs(1,m);
    if (a[1].size()) r=m; else l=m+1;
  }
  printf("%d\n",l);
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:67:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&n);
                 ^
./Main.cpp:70:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&x,&y);
                        ^

Judge Result