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Submission #394655

# Submission time Handle Problem Language Result Execution time Memory
394655 2021-04-27T06:56:06 Z Hossein29 Network (BOI15_net) C++14
100 / 100
 690 ms 62916 KB 
#include <bits/stdc++.h>
#define int long long
#define pb push_back
using namespace std;

const int maxn = 5e5+10;
const int inf = 1e18;
const int mod = 1e9+7;

int n,cnt,root(-1);
int pendant[2][maxn],deg[maxn]; // 0 -> max , 1 -> sum
vector<int>G[maxn];
vector<int>ans;

void dfs(int v,int par){
    for(int b : G[v]){
        if(b == par) continue;
        dfs(b,v);
        pendant[1][v] += pendant[1][b];
        pendant[0][v] = max(pendant[0][v],pendant[1][b]);
    }
    if(deg[v] == 1){
        pendant[1][v]++;
    }
    pendant[0][v] = max(pendant[0][v],cnt-pendant[1][v]);
    if(pendant[0][v] <= cnt/2 && root == -1 && deg[v] != 1)
        root = v;
}

void dfss(int v,int par){
    if(deg[v] == 1)
        ans.pb(v);
    for(int b : G[v]){
        if(b == par) continue;
        dfss(b,v);
    }
}

int32_t main(){
    ios:: sync_with_stdio(0),cin.tie(0),cout.tie(0);
    ////////////////////////////////////////////////
    cin >> n;
    for(int i = 1;i<n;i++){
        int a,b; cin >> a >> b;
        G[a].pb(b),G[b].pb(a);
        deg[a]++,deg[b]++;
    }
    for(int i = 1;i<=n;i++){
        if(deg[i] == 1){
            cnt++;
        }
    }
    dfs(1,-1);
    dfss(root,-1);
    int sz = ans.size();
    if(sz&1){
        cout << (sz+1)/2 << "\n";
        int len = (sz+1)/2;
        for(int i = 0;i<(sz+1)/2;i++){
            cout << ans[i] << " " << ans[min(i+len,sz-1)] << "\n";
        }
    }
    else{
        cout << sz/2 << "\n";
        int len = sz/2;
        for(int i = 0;i<sz/2;i++){
            cout << ans[i] << " " << ans[i+len] << "\n";
        }
    }
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 7 ms 12028 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 7 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12020 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 7 ms 11980 KB Output is correct
10 Correct 7 ms 11980 KB Output is correct
11 Correct 7 ms 11992 KB Output is correct
12 Correct 7 ms 11980 KB Output is correct
13 Correct 8 ms 11980 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 7 ms 11980 KB Output is correct
16 Correct 8 ms 12020 KB Output is correct
17 Correct 7 ms 11980 KB Output is correct
18 Correct 7 ms 11980 KB Output is correct
19 Correct 7 ms 12084 KB Output is correct
20 Correct 7 ms 11980 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 7 ms 12028 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 7 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12020 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 7 ms 11980 KB Output is correct
10 Correct 7 ms 11980 KB Output is correct
11 Correct 7 ms 11992 KB Output is correct
12 Correct 7 ms 11980 KB Output is correct
13 Correct 8 ms 11980 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 7 ms 11980 KB Output is correct
16 Correct 8 ms 12020 KB Output is correct
17 Correct 7 ms 11980 KB Output is correct
18 Correct 7 ms 11980 KB Output is correct
19 Correct 7 ms 12084 KB Output is correct
20 Correct 7 ms 11980 KB Output is correct
21 Correct 7 ms 11980 KB Output is correct
22 Correct 8 ms 12236 KB Output is correct
23 Correct 10 ms 12244 KB Output is correct
24 Correct 8 ms 12236 KB Output is correct
25 Correct 8 ms 12236 KB Output is correct
26 Correct 8 ms 12200 KB Output is correct
27 Correct 11 ms 12192 KB Output is correct
28 Correct 9 ms 12240 KB Output is correct
29 Correct 8 ms 12112 KB Output is correct
30 Correct 8 ms 11980 KB Output is correct
31 Correct 8 ms 12236 KB Output is correct
32 Correct 7 ms 11980 KB Output is correct
33 Correct 7 ms 11980 KB Output is correct
34 Correct 8 ms 11980 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 8 ms 11980 KB Output is correct
37 Correct 8 ms 12108 KB Output is correct
38 Correct 8 ms 12180 KB Output is correct
39 Correct 8 ms 12032 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 7 ms 12088 KB Output is correct
42 Correct 8 ms 12108 KB Output is correct
43 Correct 8 ms 12108 KB Output is correct
44 Correct 8 ms 11980 KB Output is correct
45 Correct 8 ms 12108 KB Output is correct
46 Correct 8 ms 12156 KB Output is correct
47 Correct 7 ms 11980 KB Output is correct
48 Correct 8 ms 12108 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11980 KB Output is correct
52 Correct 9 ms 12108 KB Output is correct
53 Correct 8 ms 12108 KB Output is correct
54 Correct 7 ms 12020 KB Output is correct
55 Correct 7 ms 12108 KB Output is correct
56 Correct 7 ms 11980 KB Output is correct
57 Correct 8 ms 12108 KB Output is correct
58 Correct 10 ms 12208 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 7 ms 12028 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 7 ms 11980 KB Output is correct
6 Correct 8 ms 11980 KB Output is correct
7 Correct 8 ms 12020 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 7 ms 11980 KB Output is correct
10 Correct 7 ms 11980 KB Output is correct
11 Correct 7 ms 11992 KB Output is correct
12 Correct 7 ms 11980 KB Output is correct
13 Correct 8 ms 11980 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 7 ms 11980 KB Output is correct
16 Correct 8 ms 12020 KB Output is correct
17 Correct 7 ms 11980 KB Output is correct
18 Correct 7 ms 11980 KB Output is correct
19 Correct 7 ms 12084 KB Output is correct
20 Correct 7 ms 11980 KB Output is correct
21 Correct 7 ms 11980 KB Output is correct
22 Correct 8 ms 12236 KB Output is correct
23 Correct 10 ms 12244 KB Output is correct
24 Correct 8 ms 12236 KB Output is correct
25 Correct 8 ms 12236 KB Output is correct
26 Correct 8 ms 12200 KB Output is correct
27 Correct 11 ms 12192 KB Output is correct
28 Correct 9 ms 12240 KB Output is correct
29 Correct 8 ms 12112 KB Output is correct
30 Correct 8 ms 11980 KB Output is correct
31 Correct 8 ms 12236 KB Output is correct
32 Correct 7 ms 11980 KB Output is correct
33 Correct 7 ms 11980 KB Output is correct
34 Correct 8 ms 11980 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 8 ms 11980 KB Output is correct
37 Correct 8 ms 12108 KB Output is correct
38 Correct 8 ms 12180 KB Output is correct
39 Correct 8 ms 12032 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 7 ms 12088 KB Output is correct
42 Correct 8 ms 12108 KB Output is correct
43 Correct 8 ms 12108 KB Output is correct
44 Correct 8 ms 11980 KB Output is correct
45 Correct 8 ms 12108 KB Output is correct
46 Correct 8 ms 12156 KB Output is correct
47 Correct 7 ms 11980 KB Output is correct
48 Correct 8 ms 12108 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11980 KB Output is correct
52 Correct 9 ms 12108 KB Output is correct
53 Correct 8 ms 12108 KB Output is correct
54 Correct 7 ms 12020 KB Output is correct
55 Correct 7 ms 12108 KB Output is correct
56 Correct 7 ms 11980 KB Output is correct
57 Correct 8 ms 12108 KB Output is correct
58 Correct 10 ms 12208 KB Output is correct
59 Correct 505 ms 45104 KB Output is correct
60 Correct 596 ms 48464 KB Output is correct
61 Correct 9 ms 11980 KB Output is correct
62 Correct 9 ms 11980 KB Output is correct
63 Correct 406 ms 40784 KB Output is correct
64 Correct 9 ms 12620 KB Output is correct
65 Correct 19 ms 14824 KB Output is correct
66 Correct 198 ms 35136 KB Output is correct
67 Correct 682 ms 62916 KB Output is correct
68 Correct 662 ms 62260 KB Output is correct
69 Correct 16 ms 13260 KB Output is correct
70 Correct 107 ms 25028 KB Output is correct
71 Correct 392 ms 50740 KB Output is correct
72 Correct 428 ms 49688 KB Output is correct
73 Correct 128 ms 21624 KB Output is correct
74 Correct 592 ms 46192 KB Output is correct
75 Correct 39 ms 16316 KB Output is correct
76 Correct 417 ms 50532 KB Output is correct
77 Correct 393 ms 50788 KB Output is correct
78 Correct 41 ms 16764 KB Output is correct
79 Correct 690 ms 57512 KB Output is correct
80 Correct 9 ms 12364 KB Output is correct
81 Correct 135 ms 24500 KB Output is correct
82 Correct 500 ms 48488 KB Output is correct
83 Correct 595 ms 46212 KB Output is correct
84 Correct 593 ms 46392 KB Output is correct
85 Correct 587 ms 46256 KB Output is correct
86 Correct 594 ms 48536 KB Output is correct
87 Correct 625 ms 48636 KB Output is correct