Submission #46594

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
46594	2018-04-21T19:32:52 Z	alexpetrescu	Network (BOI15_net)	C++14	100 / 100	795 ms	158208 KB

#include <cstdio>
#include <vector>

#define MAXN 500000

std::vector < int > g[MAXN + 1], v;
int s[MAXN + 1], cost[MAXN + 1];
bool viz[MAXN + 1], done[MAXN + 1];

void dfs(int x) {
    s[x] = g[x].size() == 1;
    viz[x] = 1;
    for (auto &y : g[x]) {
        if (viz[y] == 0) {
            dfs(y);
            s[x] += s[y];
            cost[x] = std::max(cost[x], s[y]);
        }
    }
}

void dfs2(int x) {
    if (g[x].size() == 1)
        v.push_back(x);
    done[x] = 1;
    for (auto &y : g[x])
        if (done[y] == 0)
            dfs2(y);
}

int main() {
    int n;
    scanf("%d", &n);

    for (int i = 1; i < n; i++) {
        int x, y;
        scanf("%d%d", &x, &y);

        g[x].push_back(y);
        g[y].push_back(x);
    }

    dfs(1);

    int ans = n + 1, r = 0;
    for (int i = 1; i <= n; i++) {
        if (g[i].size() != 1) {
            int val = std::max(cost[i], s[1] - s[i]);
            if (val < ans)
                ans = val, r = i;
        }
    }

    printf("%d\n", (s[1] + 1) / 2);
    dfs2(r);
    int k = v.size() / 2;
    for (int i = 0; i < k; i++)
        printf("%d %d\n", v[i], v[i + k]);
    if (v.size() % 2)
        printf("%d %d\n", v.back(), v[0]);

    return 0;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:33:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
net.cpp:37:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	12 ms	12024 KB	Output is correct
2	Correct	10 ms	12144 KB	Output is correct
3	Correct	10 ms	12256 KB	Output is correct
4	Correct	11 ms	12308 KB	Output is correct
5	Correct	10 ms	12400 KB	Output is correct
6	Correct	10 ms	12400 KB	Output is correct
7	Correct	11 ms	12512 KB	Output is correct
8	Correct	10 ms	12512 KB	Output is correct
9	Correct	10 ms	12512 KB	Output is correct
10	Correct	10 ms	12512 KB	Output is correct
11	Correct	10 ms	12512 KB	Output is correct
12	Correct	10 ms	12512 KB	Output is correct
13	Correct	10 ms	12512 KB	Output is correct
14	Correct	10 ms	12512 KB	Output is correct
15	Correct	10 ms	12512 KB	Output is correct
16	Correct	10 ms	12512 KB	Output is correct
17	Correct	10 ms	12512 KB	Output is correct
18	Correct	10 ms	12512 KB	Output is correct
19	Correct	10 ms	12512 KB	Output is correct
20	Correct	11 ms	12540 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	12 ms	12024 KB	Output is correct
2	Correct	10 ms	12144 KB	Output is correct
3	Correct	10 ms	12256 KB	Output is correct
4	Correct	11 ms	12308 KB	Output is correct
5	Correct	10 ms	12400 KB	Output is correct
6	Correct	10 ms	12400 KB	Output is correct
7	Correct	11 ms	12512 KB	Output is correct
8	Correct	10 ms	12512 KB	Output is correct
9	Correct	10 ms	12512 KB	Output is correct
10	Correct	10 ms	12512 KB	Output is correct
11	Correct	10 ms	12512 KB	Output is correct
12	Correct	10 ms	12512 KB	Output is correct
13	Correct	10 ms	12512 KB	Output is correct
14	Correct	10 ms	12512 KB	Output is correct
15	Correct	10 ms	12512 KB	Output is correct
16	Correct	10 ms	12512 KB	Output is correct
17	Correct	10 ms	12512 KB	Output is correct
18	Correct	10 ms	12512 KB	Output is correct
19	Correct	10 ms	12512 KB	Output is correct
20	Correct	11 ms	12540 KB	Output is correct
21	Correct	10 ms	12540 KB	Output is correct
22	Correct	14 ms	12592 KB	Output is correct
23	Correct	11 ms	12628 KB	Output is correct
24	Correct	11 ms	12664 KB	Output is correct
25	Correct	14 ms	12684 KB	Output is correct
26	Correct	11 ms	12716 KB	Output is correct
27	Correct	12 ms	12788 KB	Output is correct
28	Correct	12 ms	12788 KB	Output is correct
29	Correct	12 ms	12788 KB	Output is correct
30	Correct	10 ms	12788 KB	Output is correct
31	Correct	12 ms	12788 KB	Output is correct
32	Correct	10 ms	12788 KB	Output is correct
33	Correct	11 ms	12788 KB	Output is correct
34	Correct	10 ms	12788 KB	Output is correct
35	Correct	10 ms	12788 KB	Output is correct
36	Correct	10 ms	12788 KB	Output is correct
37	Correct	11 ms	12828 KB	Output is correct
38	Correct	11 ms	12828 KB	Output is correct
39	Correct	11 ms	12912 KB	Output is correct
40	Correct	11 ms	12912 KB	Output is correct
41	Correct	10 ms	12912 KB	Output is correct
42	Correct	11 ms	12912 KB	Output is correct
43	Correct	11 ms	12912 KB	Output is correct
44	Correct	11 ms	12912 KB	Output is correct
45	Correct	10 ms	12912 KB	Output is correct
46	Correct	11 ms	12932 KB	Output is correct
47	Correct	10 ms	12932 KB	Output is correct
48	Correct	11 ms	12932 KB	Output is correct
49	Correct	13 ms	12940 KB	Output is correct
50	Correct	10 ms	12940 KB	Output is correct
51	Correct	10 ms	12940 KB	Output is correct
52	Correct	13 ms	12940 KB	Output is correct
53	Correct	11 ms	12940 KB	Output is correct
54	Correct	11 ms	12940 KB	Output is correct
55	Correct	11 ms	12940 KB	Output is correct
56	Correct	13 ms	12940 KB	Output is correct
57	Correct	11 ms	12956 KB	Output is correct
58	Correct	12 ms	13060 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	12 ms	12024 KB	Output is correct
2	Correct	10 ms	12144 KB	Output is correct
3	Correct	10 ms	12256 KB	Output is correct
4	Correct	11 ms	12308 KB	Output is correct
5	Correct	10 ms	12400 KB	Output is correct
6	Correct	10 ms	12400 KB	Output is correct
7	Correct	11 ms	12512 KB	Output is correct
8	Correct	10 ms	12512 KB	Output is correct
9	Correct	10 ms	12512 KB	Output is correct
10	Correct	10 ms	12512 KB	Output is correct
11	Correct	10 ms	12512 KB	Output is correct
12	Correct	10 ms	12512 KB	Output is correct
13	Correct	10 ms	12512 KB	Output is correct
14	Correct	10 ms	12512 KB	Output is correct
15	Correct	10 ms	12512 KB	Output is correct
16	Correct	10 ms	12512 KB	Output is correct
17	Correct	10 ms	12512 KB	Output is correct
18	Correct	10 ms	12512 KB	Output is correct
19	Correct	10 ms	12512 KB	Output is correct
20	Correct	11 ms	12540 KB	Output is correct
21	Correct	10 ms	12540 KB	Output is correct
22	Correct	14 ms	12592 KB	Output is correct
23	Correct	11 ms	12628 KB	Output is correct
24	Correct	11 ms	12664 KB	Output is correct
25	Correct	14 ms	12684 KB	Output is correct
26	Correct	11 ms	12716 KB	Output is correct
27	Correct	12 ms	12788 KB	Output is correct
28	Correct	12 ms	12788 KB	Output is correct
29	Correct	12 ms	12788 KB	Output is correct
30	Correct	10 ms	12788 KB	Output is correct
31	Correct	12 ms	12788 KB	Output is correct
32	Correct	10 ms	12788 KB	Output is correct
33	Correct	11 ms	12788 KB	Output is correct
34	Correct	10 ms	12788 KB	Output is correct
35	Correct	10 ms	12788 KB	Output is correct
36	Correct	10 ms	12788 KB	Output is correct
37	Correct	11 ms	12828 KB	Output is correct
38	Correct	11 ms	12828 KB	Output is correct
39	Correct	11 ms	12912 KB	Output is correct
40	Correct	11 ms	12912 KB	Output is correct
41	Correct	10 ms	12912 KB	Output is correct
42	Correct	11 ms	12912 KB	Output is correct
43	Correct	11 ms	12912 KB	Output is correct
44	Correct	11 ms	12912 KB	Output is correct
45	Correct	10 ms	12912 KB	Output is correct
46	Correct	11 ms	12932 KB	Output is correct
47	Correct	10 ms	12932 KB	Output is correct
48	Correct	11 ms	12932 KB	Output is correct
49	Correct	13 ms	12940 KB	Output is correct
50	Correct	10 ms	12940 KB	Output is correct
51	Correct	10 ms	12940 KB	Output is correct
52	Correct	13 ms	12940 KB	Output is correct
53	Correct	11 ms	12940 KB	Output is correct
54	Correct	11 ms	12940 KB	Output is correct
55	Correct	11 ms	12940 KB	Output is correct
56	Correct	13 ms	12940 KB	Output is correct
57	Correct	11 ms	12956 KB	Output is correct
58	Correct	12 ms	13060 KB	Output is correct
59	Correct	493 ms	41224 KB	Output is correct
60	Correct	597 ms	50376 KB	Output is correct
61	Correct	11 ms	50376 KB	Output is correct
62	Correct	11 ms	50376 KB	Output is correct
63	Correct	448 ms	50936 KB	Output is correct
64	Correct	15 ms	50936 KB	Output is correct
65	Correct	27 ms	50936 KB	Output is correct
66	Correct	252 ms	50936 KB	Output is correct
67	Correct	795 ms	73140 KB	Output is correct
68	Correct	757 ms	78712 KB	Output is correct
69	Correct	18 ms	78712 KB	Output is correct
70	Correct	120 ms	78712 KB	Output is correct
71	Correct	401 ms	81696 KB	Output is correct
72	Correct	426 ms	89040 KB	Output is correct
73	Correct	189 ms	89040 KB	Output is correct
74	Correct	637 ms	94064 KB	Output is correct
75	Correct	42 ms	94064 KB	Output is correct
76	Correct	416 ms	105308 KB	Output is correct
77	Correct	405 ms	110044 KB	Output is correct
78	Correct	48 ms	110044 KB	Output is correct
79	Correct	793 ms	119788 KB	Output is correct
80	Correct	12 ms	119788 KB	Output is correct
81	Correct	135 ms	119788 KB	Output is correct
82	Correct	514 ms	125840 KB	Output is correct
83	Correct	728 ms	130484 KB	Output is correct
84	Correct	640 ms	137224 KB	Output is correct
85	Correct	661 ms	143800 KB	Output is correct
86	Correct	638 ms	151596 KB	Output is correct
87	Correct	568 ms	158208 KB	Output is correct

Submission #46594

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0