oj.uz

Submission #40609

# Submission time Handle Problem Language Result Execution time Memory
40609 2018-02-05T16:47:55 Z Hassoony Network (BOI15_net) C++14
18 / 100
 24 ms 24320 KB 
#include<bits/stdc++.h>
#include<unordered_map>
using namespace std;
typedef long long ll;
const ll inf=(1ll<<60);
const ll mod=1e9+7;
const int MX=5e5+9;
int n,m,subtree[MX],par[MX],leaf[MX];
vector<int>v[MX],v1[MX];
void dfs_size(int x,int p){
    subtree[x]=1;par[x]=p;
    for(auto pp:v[x]){
        if(pp==p)continue;
        dfs_size(pp,x);
        subtree[x]+=subtree[pp];
    }
}
int centroid(int x){
    dfs_size(x,-1);
    int S=subtree[x],idx;
    queue<int>q;
    q.push(x);
    while(!q.empty()){
        int nxt=q.front();q.pop();
        int s=subtree[x]-subtree[nxt];
        for(auto pp:v[nxt]){
            if(pp==par[nxt])continue;
            s=max(s,subtree[pp]);
            q.push(pp);
        }
        if(S>s){
            S=s;
            idx=nxt;
        }
    }
    return idx;
}
int x,y,cen,timer;
void dfs(int x,int p){
    if(leaf[x]){
        v1[timer].push_back(x);
        return;
    }
    for(auto pp:v[x]){
        if(pp==p)continue;
        dfs(pp,x);
        if(x==cen)timer++;
    }
}
int leaves;
int cel(int x,int y){
    if(x%y==0)return x/y;
    return x/y+1;
}
int main(){
    scanf("%d",&n);
    if(n==1){
        puts("0");
        return 0;
    }
    if(n==2){
        puts("1");
        cout<<1<<" "<<2<<endl;
        return 0;
    }
    for(int i=0;i<n-1;i++){
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(int i=1;i<=n;i++){
        if(v[i].size()==1){
            leaf[i]=1;
            leaves++;
        }
    }
    int idx=1;
    for(int i=1;i<=n;i++)if(!leaf[i])idx=i;
    cen=centroid(idx);
    dfs(cen,-1);
    priority_queue<pair<int,int> >pq;
    for(int i=0;i<timer;i++){
        pq.push({v1[i].size(),i});
    }
    printf("%d\n",cel(leaves,2));
    while(pq.size()>1){
        int com1=pq.top().second,sz1=pq.top().first;pq.pop();
        int com2=pq.top().second,sz2=pq.top().first;pq.pop();
        printf("%d %d\n",v1[com1][sz1-1],v1[com2][sz2-1]);
        --sz1;--sz2;
        if(sz1>0)pq.push({sz1,com1});
        if(sz2>0)pq.push({sz2,com2});
    }
    if(!pq.empty()){
        printf("%d %d\n",v1[pq.top().second][0],cen);
    }
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:56:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
                   ^
net.cpp:67:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x,&y);
                            ^
net.cpp: In function 'int centroid(int)':
net.cpp:36:12: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return idx;
            ^

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23820 KB Output is correct
2 Correct 21 ms 23904 KB Output is correct
3 Correct 19 ms 23904 KB Output is correct
4 Correct 22 ms 23976 KB Output is correct
5 Correct 21 ms 23976 KB Output is correct
6 Correct 24 ms 23976 KB Output is correct
7 Correct 21 ms 23976 KB Output is correct
8 Correct 19 ms 24048 KB Output is correct
9 Correct 18 ms 24104 KB Output is correct
10 Correct 19 ms 24104 KB Output is correct
11 Correct 23 ms 24104 KB Output is correct
12 Correct 20 ms 24104 KB Output is correct
13 Correct 22 ms 24104 KB Output is correct
14 Correct 20 ms 24104 KB Output is correct
15 Correct 22 ms 24104 KB Output is correct
16 Correct 20 ms 24104 KB Output is correct
17 Correct 21 ms 24104 KB Output is correct
18 Correct 22 ms 24104 KB Output is correct
19 Correct 19 ms 24104 KB Output is correct
20 Correct 21 ms 24104 KB Output is correct

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23820 KB Output is correct
2 Correct 21 ms 23904 KB Output is correct
3 Correct 19 ms 23904 KB Output is correct
4 Correct 22 ms 23976 KB Output is correct
5 Correct 21 ms 23976 KB Output is correct
6 Correct 24 ms 23976 KB Output is correct
7 Correct 21 ms 23976 KB Output is correct
8 Correct 19 ms 24048 KB Output is correct
9 Correct 18 ms 24104 KB Output is correct
10 Correct 19 ms 24104 KB Output is correct
11 Correct 23 ms 24104 KB Output is correct
12 Correct 20 ms 24104 KB Output is correct
13 Correct 22 ms 24104 KB Output is correct
14 Correct 20 ms 24104 KB Output is correct
15 Correct 22 ms 24104 KB Output is correct
16 Correct 20 ms 24104 KB Output is correct
17 Correct 21 ms 24104 KB Output is correct
18 Correct 22 ms 24104 KB Output is correct
19 Correct 19 ms 24104 KB Output is correct
20 Correct 21 ms 24104 KB Output is correct
21 Correct 21 ms 24104 KB Output is correct
22 Correct 23 ms 24156 KB Output is correct
23 Correct 20 ms 24156 KB Output is correct
24 Correct 20 ms 24320 KB Output is correct
25 Correct 23 ms 24320 KB Output is correct
26 Correct 21 ms 24320 KB Output is correct
27 Correct 20 ms 24320 KB Output is correct
28 Correct 20 ms 24320 KB Output is correct
29 Correct 21 ms 24320 KB Output is correct
30 Correct 21 ms 24320 KB Output is correct
31 Correct 21 ms 24320 KB Output is correct
32 Correct 19 ms 24320 KB Output is correct
33 Correct 20 ms 24320 KB Output is correct
34 Correct 20 ms 24320 KB Output is correct
35 Correct 22 ms 24320 KB Output is correct
36 Correct 21 ms 24320 KB Output is correct
37 Incorrect 19 ms 24320 KB Unexpected end of file - int32 expected
38 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23820 KB Output is correct
2 Correct 21 ms 23904 KB Output is correct
3 Correct 19 ms 23904 KB Output is correct
4 Correct 22 ms 23976 KB Output is correct
5 Correct 21 ms 23976 KB Output is correct
6 Correct 24 ms 23976 KB Output is correct
7 Correct 21 ms 23976 KB Output is correct
8 Correct 19 ms 24048 KB Output is correct
9 Correct 18 ms 24104 KB Output is correct
10 Correct 19 ms 24104 KB Output is correct
11 Correct 23 ms 24104 KB Output is correct
12 Correct 20 ms 24104 KB Output is correct
13 Correct 22 ms 24104 KB Output is correct
14 Correct 20 ms 24104 KB Output is correct
15 Correct 22 ms 24104 KB Output is correct
16 Correct 20 ms 24104 KB Output is correct
17 Correct 21 ms 24104 KB Output is correct
18 Correct 22 ms 24104 KB Output is correct
19 Correct 19 ms 24104 KB Output is correct
20 Correct 21 ms 24104 KB Output is correct
21 Correct 21 ms 24104 KB Output is correct
22 Correct 23 ms 24156 KB Output is correct
23 Correct 20 ms 24156 KB Output is correct
24 Correct 20 ms 24320 KB Output is correct
25 Correct 23 ms 24320 KB Output is correct
26 Correct 21 ms 24320 KB Output is correct
27 Correct 20 ms 24320 KB Output is correct
28 Correct 20 ms 24320 KB Output is correct
29 Correct 21 ms 24320 KB Output is correct
30 Correct 21 ms 24320 KB Output is correct
31 Correct 21 ms 24320 KB Output is correct
32 Correct 19 ms 24320 KB Output is correct
33 Correct 20 ms 24320 KB Output is correct
34 Correct 20 ms 24320 KB Output is correct
35 Correct 22 ms 24320 KB Output is correct
36 Correct 21 ms 24320 KB Output is correct
37 Incorrect 19 ms 24320 KB Unexpected end of file - int32 expected
38 Halted 0 ms 0 KB -