#define DEBUG 1
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
int t,m;
vi adjList[1000001];
int parent[1000001];
int dp[1000001],dp2[1000001];
int doDFS(int u,int p) {
int i;
int m1 = 0,m2 = 0,c = 0;
parent[u] = p;
for (i = 0; i < adjList[u].size(); i++) {
int v = adjList[u][i];
if (v != p) {
doDFS(v,u);
if (dp[v] >= m1) m2 = m1,m1 = dp[v];
else if (dp[v] >= m2) m2 = dp[v];
c++;
}
}
dp[u] = m2+c;
return dp[u];
}
vi path;
int doDFS2(int u,int p) {
int i;
if (u != t) {
int s = 0;
for (i = 1; i < path.size(); i++) s += adjList[path[i]].size()-2;
if (p == t) dp2[u] = 0;
else {
int a = -1,b = -1;
for (i = 0; i < adjList[p].size(); i++) {
int v = adjList[p][i];
if ((v != parent[p]) && (v != u)) {
if (dp[v] >= a) b = a,a = dp[v];
else if (dp[v] >= b) b = dp[v];
}
}
int m1 = max(dp2[p],a+s);
int m2 = max(dp2[p]+1,b+s);
dp2[u] = min(m1,m2);
}
}
path.pb(u);
for (i = 0; i < adjList[u].size(); i++) {
int v = adjList[u][i];
if (v != p) doDFS2(v,u);
}
path.pop_back();
return 0;
}
int main() {
int i;
int n;
int a,b;
scanf("%d %d %d",&n,&t,&m),t--,m--;
for (i = 1; i < n; i++) {
scanf("%d %d",&a,&b);
a--,b--;
adjList[a].pb(b);
adjList[b].pb(a);
}
adjList[m].pb(n);
adjList[n].pb(m);
doDFS(t,-1);
doDFS2(t,-1);
//printArr(dp,n+1);
//printArr(dp2,n+1);
printf("%d\n",dp2[n]);
return 0;
}
Compilation message
mousetrap.cpp: In function 'int doDFS(int, int)':
mousetrap.cpp:66:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (i = 0; i < adjList[u].size(); i++) {
~~^~~~~~~~~~~~~~~~~~~
mousetrap.cpp: In function 'int doDFS2(int, int)':
mousetrap.cpp:83:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (i = 1; i < path.size(); i++) s += adjList[path[i]].size()-2;
~~^~~~~~~~~~~~~
mousetrap.cpp:87:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (i = 0; i < adjList[p].size(); i++) {
~~^~~~~~~~~~~~~~~~~~~
mousetrap.cpp:100:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (i = 0; i < adjList[u].size(); i++) {
~~^~~~~~~~~~~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:111:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d %d",&n,&t,&m),t--,m--;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
mousetrap.cpp:113:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d",&a,&b);
~~~~~^~~~~~~~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
23 ms |
23800 KB |
Output is correct |
2 |
Correct |
23 ms |
23980 KB |
Output is correct |
3 |
Correct |
23 ms |
23980 KB |
Output is correct |
4 |
Correct |
23 ms |
24020 KB |
Output is correct |
5 |
Incorrect |
23 ms |
24096 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
512 ms |
67192 KB |
Output is correct |
2 |
Correct |
503 ms |
67192 KB |
Output is correct |
3 |
Correct |
1488 ms |
68332 KB |
Output is correct |
4 |
Correct |
665 ms |
68332 KB |
Output is correct |
5 |
Correct |
1387 ms |
68332 KB |
Output is correct |
6 |
Correct |
1373 ms |
68536 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
23 ms |
23800 KB |
Output is correct |
2 |
Correct |
23 ms |
23980 KB |
Output is correct |
3 |
Correct |
23 ms |
23980 KB |
Output is correct |
4 |
Correct |
23 ms |
24020 KB |
Output is correct |
5 |
Incorrect |
23 ms |
24096 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
23 ms |
23800 KB |
Output is correct |
2 |
Correct |
23 ms |
23980 KB |
Output is correct |
3 |
Correct |
23 ms |
23980 KB |
Output is correct |
4 |
Correct |
23 ms |
24020 KB |
Output is correct |
5 |
Incorrect |
23 ms |
24096 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |