// from duckindog wth depression
#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5 + 10;
int n;
vector<int> ad[N];
bool dd[N];
int st, ed;
void locate(int u, int pre = 0) {
dd[u] = 1;
for (int v : ad[u]) {
if (v == pre) continue;
if (dd[v]) {
st = u, ed = v;
continue;
}
locate(v, u);
}
}
int f[N][2][2][2][2];
int dfs(int u, int pre, int sub, int par, int cst, int ced) {
if (u == ed && (par && cst || sub != ced)) return 1e6;
auto &ret = f[u][sub][par][cst][ced];
if (ret > -1) return ret; ret = sub;
bool seen = par;
if (u == ed) {
par |= cst;
seen |= cst;
}
int diff = 1e6, nv = 0;
for (int v : ad[u]) {
if (v == pre) continue;
if (par) {
ret += dfs(v, u, 0, sub, cst, ced);
}
if (!par) {
int upper = dfs(v, u, 1, sub, cst, ced);
int lower = dfs(v, u, 0, sub, cst, ced);
int differ = upper - lower;
if (differ < diff) diff = differ, nv = v;
}
}
if (nv) {
for (auto v : ad[u]) {
if (v == pre) continue;
if (!par) {
seen = 1;
if (v == nv) ret += dfs(v, u, 1, sub, cst, ced);
else ret += dfs(v, u, 0, sub, cst, ced);
}
}
}
if (!seen) ret = 1e6;
return ret;
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
if (fopen("duck.inp", "r")) {
freopen("duck.inp", "r", stdin);
freopen("duck.out", "w", stdout);
}
cin >> n;
for (int i = 1; i <= n; ++i) {
int u, v; cin >> u >> v;
ad[u].push_back(v);
ad[v].push_back(u);
} locate(1);
ad[st].erase(remove(ad[st].begin(), ad[st].end(), ed), ad[st].end());
ad[ed].erase(remove(ad[ed].begin(), ad[ed].end(), st), ad[ed].end());
memset(f, -1, sizeof f);
int answer = 1e6;
// for (int i = 0; i <= 1; ++i)
// for (int j = 0; j <= 1; ++j) cerr << dfs(st, ed, i, j, i, j) << '\n';
for (int i = 0; i <= 1; ++i)
for (int j = 0; j <= 1; ++j) answer = min(answer, dfs(st, ed, i, j, i, j));
cout << (answer >= n ? -1 : answer) << '\n';
}
Compilation message
Main.cpp: In function 'long long int dfs(long long int, long long int, long long int, long long int, long long int, long long int)':
Main.cpp:26:23: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
26 | if (u == ed && (par && cst || sub != ced)) return 1e6;
| ~~~~^~~~~~
Main.cpp:29:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
29 | if (ret > -1) return ret; ret = sub;
| ^~
Main.cpp:29:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
29 | if (ret > -1) return ret; ret = sub;
| ^~~
Main.cpp: In function 'int32_t main()':
Main.cpp:74:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
74 | freopen("duck.inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:75:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
75 | freopen("duck.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
15192 KB |
Output is correct |
2 |
Correct |
2 ms |
15196 KB |
Output is correct |
3 |
Correct |
3 ms |
15196 KB |
Output is correct |
4 |
Correct |
2 ms |
15196 KB |
Output is correct |
5 |
Correct |
137 ms |
34188 KB |
Output is correct |
6 |
Correct |
123 ms |
34028 KB |
Output is correct |
7 |
Correct |
137 ms |
34192 KB |
Output is correct |
8 |
Correct |
126 ms |
34128 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
15196 KB |
Output is correct |
2 |
Correct |
3 ms |
15196 KB |
Output is correct |
3 |
Correct |
3 ms |
15196 KB |
Output is correct |
4 |
Correct |
3 ms |
15228 KB |
Output is correct |
5 |
Correct |
3 ms |
15232 KB |
Output is correct |
6 |
Correct |
3 ms |
15196 KB |
Output is correct |
7 |
Correct |
2 ms |
15196 KB |
Output is correct |
8 |
Correct |
2 ms |
15196 KB |
Output is correct |
9 |
Correct |
3 ms |
15196 KB |
Output is correct |
10 |
Correct |
2 ms |
15196 KB |
Output is correct |
11 |
Correct |
2 ms |
15196 KB |
Output is correct |
12 |
Correct |
3 ms |
15196 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
15196 KB |
Output is correct |
2 |
Correct |
3 ms |
15196 KB |
Output is correct |
3 |
Correct |
3 ms |
15196 KB |
Output is correct |
4 |
Correct |
3 ms |
15228 KB |
Output is correct |
5 |
Correct |
3 ms |
15232 KB |
Output is correct |
6 |
Correct |
3 ms |
15196 KB |
Output is correct |
7 |
Correct |
2 ms |
15196 KB |
Output is correct |
8 |
Correct |
2 ms |
15196 KB |
Output is correct |
9 |
Correct |
3 ms |
15196 KB |
Output is correct |
10 |
Correct |
2 ms |
15196 KB |
Output is correct |
11 |
Correct |
2 ms |
15196 KB |
Output is correct |
12 |
Correct |
3 ms |
15196 KB |
Output is correct |
13 |
Correct |
4 ms |
15460 KB |
Output is correct |
14 |
Correct |
3 ms |
15452 KB |
Output is correct |
15 |
Correct |
4 ms |
15448 KB |
Output is correct |
16 |
Correct |
3 ms |
15452 KB |
Output is correct |
17 |
Correct |
3 ms |
15196 KB |
Output is correct |
18 |
Correct |
3 ms |
15452 KB |
Output is correct |
19 |
Correct |
3 ms |
15208 KB |
Output is correct |
20 |
Correct |
3 ms |
15448 KB |
Output is correct |
21 |
Correct |
3 ms |
15452 KB |
Output is correct |
22 |
Correct |
3 ms |
15452 KB |
Output is correct |
23 |
Correct |
3 ms |
15448 KB |
Output is correct |
24 |
Correct |
3 ms |
15452 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
15192 KB |
Output is correct |
2 |
Correct |
2 ms |
15196 KB |
Output is correct |
3 |
Correct |
3 ms |
15196 KB |
Output is correct |
4 |
Correct |
2 ms |
15196 KB |
Output is correct |
5 |
Correct |
137 ms |
34188 KB |
Output is correct |
6 |
Correct |
123 ms |
34028 KB |
Output is correct |
7 |
Correct |
137 ms |
34192 KB |
Output is correct |
8 |
Correct |
126 ms |
34128 KB |
Output is correct |
9 |
Correct |
3 ms |
15196 KB |
Output is correct |
10 |
Correct |
3 ms |
15196 KB |
Output is correct |
11 |
Correct |
3 ms |
15196 KB |
Output is correct |
12 |
Correct |
3 ms |
15228 KB |
Output is correct |
13 |
Correct |
3 ms |
15232 KB |
Output is correct |
14 |
Correct |
3 ms |
15196 KB |
Output is correct |
15 |
Correct |
2 ms |
15196 KB |
Output is correct |
16 |
Correct |
2 ms |
15196 KB |
Output is correct |
17 |
Correct |
3 ms |
15196 KB |
Output is correct |
18 |
Correct |
2 ms |
15196 KB |
Output is correct |
19 |
Correct |
2 ms |
15196 KB |
Output is correct |
20 |
Correct |
3 ms |
15196 KB |
Output is correct |
21 |
Correct |
4 ms |
15460 KB |
Output is correct |
22 |
Correct |
3 ms |
15452 KB |
Output is correct |
23 |
Correct |
4 ms |
15448 KB |
Output is correct |
24 |
Correct |
3 ms |
15452 KB |
Output is correct |
25 |
Correct |
3 ms |
15196 KB |
Output is correct |
26 |
Correct |
3 ms |
15452 KB |
Output is correct |
27 |
Correct |
3 ms |
15208 KB |
Output is correct |
28 |
Correct |
3 ms |
15448 KB |
Output is correct |
29 |
Correct |
3 ms |
15452 KB |
Output is correct |
30 |
Correct |
3 ms |
15452 KB |
Output is correct |
31 |
Correct |
3 ms |
15448 KB |
Output is correct |
32 |
Correct |
3 ms |
15452 KB |
Output is correct |
33 |
Correct |
80 ms |
19680 KB |
Output is correct |
34 |
Correct |
86 ms |
19548 KB |
Output is correct |
35 |
Correct |
77 ms |
19684 KB |
Output is correct |
36 |
Correct |
87 ms |
19680 KB |
Output is correct |
37 |
Correct |
19 ms |
16472 KB |
Output is correct |
38 |
Correct |
82 ms |
19792 KB |
Output is correct |
39 |
Correct |
9 ms |
15708 KB |
Output is correct |
40 |
Correct |
82 ms |
19536 KB |
Output is correct |
41 |
Correct |
46 ms |
20176 KB |
Output is correct |
42 |
Correct |
54 ms |
20296 KB |
Output is correct |
43 |
Correct |
123 ms |
35152 KB |
Output is correct |
44 |
Correct |
88 ms |
27748 KB |
Output is correct |