#include <bits/stdc++.h>
using namespace std;
const long long N = 1e5 + 2, mod = 1e9 + 7;
vector<int> adj[N];
vector<int> cy;
int dp[N][4], dp2[N][5][5];
bool vis[N];
int par[N];
int n, hi;
void cyc(int u)
{
vis[u] = 1;
for (auto v : adj[u])
{
if (v == par[u])
continue;
par[v] = u;
if (vis[v])
hi = v;
if (hi)
return;
cyc(v);
}
vis[u] = 0;
}
void calc(int u, int p)
{
bool flag = 0;
int cnt[4] = {}, sum[4] = {};
for (auto v : adj[u])
{
if (vis[v] || v == p)
continue;
calc(v, u);
for (int i = 0; i < 4; i++)
cnt[i] += (dp[v][i] == -1), sum[i] += dp[v][i];
flag = 1;
}
if (!flag)
{
dp[u][3] = dp[u][1] = 0;
dp[u][0] = dp[u][2] = -1;
return;
}
for (int i = 0; i < 4; i++)
dp[u][i] = mod;
for (auto v : adj[u])
{
if (vis[v] || v == p)
continue;
// calc dp[u][0]
if (dp[v][1] != -1 && cnt[3] - (dp[v][3] == -1) == 0)
dp[u][0] = min(dp[u][0], dp[v][1] + (sum[3] - dp[v][3]) + 2);
// calc dp[u][1]
if (cnt[3] == 0)
dp[u][1] = sum[3];
// calc dp[u][2]
if (dp[v][0] != -1 && cnt[2] - (dp[v][2] == -1) == 0)
dp[u][2] = min(dp[u][2], dp[v][0] + (sum[2] - dp[v][2]));
// calc dp[u][3]
if (cnt[2] == 0)
dp[u][3] = sum[2];
}
for (int i = 0; i < 4; i++)
dp[u][i] = (dp[u][i] == mod ? -1 : dp[u][i]);
}
/*
dp[u][0]= one dp[v][1] AND all dp[v][3] (source)
dp[u][1]= all dp[v][3] (partner)
dp[u][2]= one dp[v][0] AND all dp[v][2] (parent)
dp[u][3]= all dp[v][2] (nothing)
*/
/*
states:
0: means i am blue
1: means i am sec blue
2: i am after 1 OR 4
3: i am behind 0 OR 4
4: means i am blue and i dont want partner
*/
int solve(int ind, int lst, int st)
{
if (~dp2[ind][lst][st])
return dp2[ind][lst][st];
if (ind == cy.size())
{
if (lst == 0 && st == 1)
return 0;
if (lst == 1 && st == 2)
return 0;
if (lst == 2 && st == 3)
return 0;
if (lst == 3 && (st == 0 || st == 4))
return 0;
if (lst == 4 && st == 2)
return 0;
return mod;
}
int ret = mod;
if (ind == 0)
{
// ret = solve(ind + 1, 4, 4) + dp[cy[ind]][0];
for (int i = 0; i < 5; i++)
{
if ((i == 2 || i == 3) && dp[cy[ind]][3] != -1)
ret = min(ret, solve(ind + 1, i, i) + dp[cy[ind]][3]);
else if (i == 4 && dp[cy[ind]][0] != -1)
ret = min(ret, solve(ind + 1, i, i) + dp[cy[ind]][0]);
else if ((i == 0 || i == 1) && dp[cy[ind]][1] != -1)
ret = min(ret, solve(ind + 1, i, i) + dp[cy[ind]][1] + (i == 0) * 2);
}
}
else
{
if (lst == 0 && dp[cy[ind]][1] != -1)
ret = solve(ind + 1, 1, st) + dp[cy[ind]][1];
if (lst == 1 && dp[cy[ind]][3] != -1)
ret = solve(ind + 1, 2, st) + dp[cy[ind]][3];
if (lst == 2 && dp[cy[ind]][3] != -1)
ret = solve(ind + 1, 3, st) + dp[cy[ind]][3];
if (lst == 3 && dp[cy[ind]][1] != -1)
ret = min(ret, solve(ind + 1, 0, st) + dp[cy[ind]][1] + 2);
if (lst == 3 && dp[cy[ind]][0] != -1)
ret = min(ret, solve(ind + 1, 4, st) + dp[cy[ind]][0]);
if (lst == 4 && dp[cy[ind]][3] != -1)
ret = min(ret, solve(ind + 1, 2, st) + dp[cy[ind]][3]);
}
return dp2[ind][lst][st] = ret;
}
int main()
{
memset(dp2, -1, sizeof dp2);
cin >> n;
for (int i = 0; i < n; i++)
{
int x, y;
cin >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
}
cyc(1);
int tmp = hi;
int cnt = 0;
while (true)
{
cnt++;
if (cnt == 1e5 + 4)
{
return cout << -1, 0;
}
cy.push_back(tmp);
vis[tmp] = 1;
tmp = par[tmp];
if (tmp == hi)
break;
}
for (auto v : cy)
calc(v, 0);
int tmpp = solve(0, 0, 0); // (2 4 3)
// cout << dp[2][0] << " " << dp[4][3] << " " << dp[3][3] << " ";
if (tmpp == mod)
cout << -1;
else
cout << tmpp;
}
Compilation message
Main.cpp: In function 'int solve(int, int, int)':
Main.cpp:85:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
85 | if (ind == cy.size())
| ~~~~^~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
14424 KB |
Output is correct |
| 2 |
Correct |
3 ms |
14424 KB |
Output is correct |
| 3 |
Correct |
2 ms |
14428 KB |
Output is correct |
| 4 |
Correct |
2 ms |
14428 KB |
Output is correct |
| 5 |
Correct |
76 ms |
25992 KB |
Output is correct |
| 6 |
Correct |
75 ms |
26064 KB |
Output is correct |
| 7 |
Correct |
86 ms |
26068 KB |
Output is correct |
| 8 |
Correct |
79 ms |
26036 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
15064 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
15064 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
14424 KB |
Output is correct |
| 2 |
Correct |
3 ms |
14424 KB |
Output is correct |
| 3 |
Correct |
2 ms |
14428 KB |
Output is correct |
| 4 |
Correct |
2 ms |
14428 KB |
Output is correct |
| 5 |
Correct |
76 ms |
25992 KB |
Output is correct |
| 6 |
Correct |
75 ms |
26064 KB |
Output is correct |
| 7 |
Correct |
86 ms |
26068 KB |
Output is correct |
| 8 |
Correct |
79 ms |
26036 KB |
Output is correct |
| 9 |
Incorrect |
3 ms |
15064 KB |
Output isn't correct |
| 10 |
Halted |
0 ms |
0 KB |
- |
