oj.uz

Submission #40611

# Submission time Handle Problem Language Result Execution time Memory
40611 2018-02-05T16:54:58 Z Hassoony Network (BOI15_net) C++14
18 / 100
 33 ms 29052 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=6e5+9;
int n,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=2;
    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();
        if(sz1<=0||sz2<=0)continue;
        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 27 ms 28536 KB Output is correct
2 Correct 26 ms 28536 KB Output is correct
3 Correct 32 ms 28584 KB Output is correct
4 Correct 26 ms 28676 KB Output is correct
5 Correct 32 ms 28676 KB Output is correct
6 Correct 30 ms 28832 KB Output is correct
7 Correct 26 ms 28832 KB Output is correct
8 Correct 26 ms 28832 KB Output is correct
9 Correct 25 ms 28832 KB Output is correct
10 Correct 26 ms 28852 KB Output is correct
11 Correct 25 ms 28852 KB Output is correct
12 Correct 30 ms 28852 KB Output is correct
13 Correct 28 ms 28892 KB Output is correct
14 Correct 25 ms 28892 KB Output is correct
15 Correct 25 ms 28892 KB Output is correct
16 Correct 24 ms 28892 KB Output is correct
17 Correct 25 ms 28892 KB Output is correct
18 Correct 30 ms 28892 KB Output is correct
19 Correct 25 ms 28892 KB Output is correct
20 Correct 25 ms 28892 KB Output is correct

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 27 ms 28536 KB Output is correct
2 Correct 26 ms 28536 KB Output is correct
3 Correct 32 ms 28584 KB Output is correct
4 Correct 26 ms 28676 KB Output is correct
5 Correct 32 ms 28676 KB Output is correct
6 Correct 30 ms 28832 KB Output is correct
7 Correct 26 ms 28832 KB Output is correct
8 Correct 26 ms 28832 KB Output is correct
9 Correct 25 ms 28832 KB Output is correct
10 Correct 26 ms 28852 KB Output is correct
11 Correct 25 ms 28852 KB Output is correct
12 Correct 30 ms 28852 KB Output is correct
13 Correct 28 ms 28892 KB Output is correct
14 Correct 25 ms 28892 KB Output is correct
15 Correct 25 ms 28892 KB Output is correct
16 Correct 24 ms 28892 KB Output is correct
17 Correct 25 ms 28892 KB Output is correct
18 Correct 30 ms 28892 KB Output is correct
19 Correct 25 ms 28892 KB Output is correct
20 Correct 25 ms 28892 KB Output is correct
21 Correct 27 ms 28892 KB Output is correct
22 Correct 33 ms 29028 KB Output is correct
23 Correct 27 ms 29028 KB Output is correct
24 Correct 28 ms 29028 KB Output is correct
25 Correct 27 ms 29028 KB Output is correct
26 Correct 25 ms 29028 KB Output is correct
27 Correct 27 ms 29028 KB Output is correct
28 Correct 27 ms 29028 KB Output is correct
29 Correct 26 ms 29028 KB Output is correct
30 Correct 26 ms 29028 KB Output is correct
31 Correct 27 ms 29052 KB Output is correct
32 Correct 26 ms 29052 KB Output is correct
33 Correct 24 ms 29052 KB Output is correct
34 Correct 26 ms 29052 KB Output is correct
35 Correct 28 ms 29052 KB Output is correct
36 Correct 26 ms 29052 KB Output is correct
37 Incorrect 26 ms 29052 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 27 ms 28536 KB Output is correct
2 Correct 26 ms 28536 KB Output is correct
3 Correct 32 ms 28584 KB Output is correct
4 Correct 26 ms 28676 KB Output is correct
5 Correct 32 ms 28676 KB Output is correct
6 Correct 30 ms 28832 KB Output is correct
7 Correct 26 ms 28832 KB Output is correct
8 Correct 26 ms 28832 KB Output is correct
9 Correct 25 ms 28832 KB Output is correct
10 Correct 26 ms 28852 KB Output is correct
11 Correct 25 ms 28852 KB Output is correct
12 Correct 30 ms 28852 KB Output is correct
13 Correct 28 ms 28892 KB Output is correct
14 Correct 25 ms 28892 KB Output is correct
15 Correct 25 ms 28892 KB Output is correct
16 Correct 24 ms 28892 KB Output is correct
17 Correct 25 ms 28892 KB Output is correct
18 Correct 30 ms 28892 KB Output is correct
19 Correct 25 ms 28892 KB Output is correct
20 Correct 25 ms 28892 KB Output is correct
21 Correct 27 ms 28892 KB Output is correct
22 Correct 33 ms 29028 KB Output is correct
23 Correct 27 ms 29028 KB Output is correct
24 Correct 28 ms 29028 KB Output is correct
25 Correct 27 ms 29028 KB Output is correct
26 Correct 25 ms 29028 KB Output is correct
27 Correct 27 ms 29028 KB Output is correct
28 Correct 27 ms 29028 KB Output is correct
29 Correct 26 ms 29028 KB Output is correct
30 Correct 26 ms 29028 KB Output is correct
31 Correct 27 ms 29052 KB Output is correct
32 Correct 26 ms 29052 KB Output is correct
33 Correct 24 ms 29052 KB Output is correct
34 Correct 26 ms 29052 KB Output is correct
35 Correct 28 ms 29052 KB Output is correct
36 Correct 26 ms 29052 KB Output is correct
37 Incorrect 26 ms 29052 KB Unexpected end of file - int32 expected
38 Halted 0 ms 0 KB -