Submission #1135287
Source Code Expand
// ba mei zi !
#include<bits/stdc++.h>
#define HEAP priority_queue
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define per(i, n) for(int i = (n) - 1; i >= 0 ; --i)
#define forn(i, l, r) for(int i = (l); i <= (r); ++i)
#define nrof(i, r, l) for(int i = (r); i >= (l); --i)
#define FOR(a, b) for(auto (a): (b))
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define X first
#define Y second
#define eps 1e-6
#define pi 3.1415926535897932384626433832795
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(), x.end()
#define FILL(a, b) memset((a), (b), sizeof((a)))
#define MCPY(a, b) memcpy((a), (b), sizeof((b)))
using namespace std;
typedef long long LL;
typedef double flt;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef pair<int,int> pii;
typedef pair<int,LL> pil;
typedef pair<LL,int> pli;
typedef pair<LL,LL> pll;
typedef vector<pil> vil;
typedef vector<pii> vii;
typedef vector<pli> vli;
typedef vector<pll> vll;
const int iinf = 1e9 + 7;
const LL linf = 1ll << 60;
const flt dinf = 1e60;
template <typename T>
inline void scf(T &x)
{
bool f = 0; x = 0; char c = getchar();
while((c < '0' || c > '9') && c != '-') c = getchar();
if(c == '-') { f = 1; c = getchar(); }
while(c >= '0' && c <= '9') { x = x * 10 + c - '0'; c = getchar(); }
if(f) x = -x; return;
}
template <typename T1, typename T2>
void scf(T1 &x, T2 &y) { scf(x); return scf(y); }
template <typename T1, typename T2, typename T3>
void scf(T1 &x, T2 &y, T3 &z) { scf(x); scf(y); return scf(z); }
template <typename T1, typename T2, typename T3, typename T4>
void scf(T1 &x, T2 &y, T3 &z, T4 &w) { scf(x); scf(y); scf(z); return scf(w); }
inline char mygetchar(){ char c = getchar(); while(c == ' ' || c == '\n') c = getchar(); return c; }
template <typename T>
void chkmax(T &x, const T &y){ if(y > x) x = y; return; }
template <typename T>
void chkmin(T &x, const T &y){ if(y < x) x = y; return; }
#ifdef ONLINE_JUDGE
#define debug(x,c) ;
#else
#define DEBUG
#define debug(x,c) cerr<<#x<<"="<<x<<c;
#endif
//---------------------------head----------------------------
const int N = 1e3 + 100;
const int mod = 1e9 + 7;
int n, diameter_length, min_D;
int dp[N][N], tag[N][N], current_time;
vi g[N];
vi diameter_path;
namespace TREE
{
int par[N], dep[N];
void dfs(int u = 1, int fa = 0)
{
par[u] = fa;
dep[u] = dep[fa] + 1;
for(int v: g[u]) if(v != fa) dfs(v, u);
return;
}
void get_diameter()
{
dfs();
int mx = -1, S, T;
forn(i, 1, n) if(dep[i] > mx) mx = dep[i], S = i;
dfs(S);
mx = -1;
forn(i, 1, n) if(dep[i] > mx) mx = dep[i], T = i;
diameter_length = dep[T] - 1;
min_D = dep[T] >> 1;
int u = T;
while(u != S) diameter_path.pb(u), u = par[u];
diameter_path.pb(S);
return;
}
}
void MEI()
{
scf(n);
rep(i, n - 1)
{
int u, v;
scf(u, v);
g[u].pb(v);
g[v].pb(u);
}
TREE::get_diameter();
return;
}
namespace Bamboo
{
void solve()
{
dp[0][0] = 1;
forn(i, 1, n - 1)
{
dp[i][0] = dp[i][i] = 1;
forn(j, 1, i - 1) dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % mod;
}
printf("%d\n", (n & 1) ? dp[n - 1][min_D] : (dp[n - 1][min_D] * 2 % mod));
return;
}
}
void DP(int u, int par, int max_down, int max_up)
{
if(tag[u][max_down] == current_time) return;
tag[u][max_down] = current_time;
int &t = dp[u][max_down];
t = 1;
for(int v: g[u]) if(v != par)
{
int foo = 0;
if(max_down) DP(v, u, max_down - 1, max_up), foo += dp[v][max_down - 1];
if(max_up) DP(v, u, max_down, max_up - 1), foo += dp[v][max_down];
t = 1ll * t * foo % mod;
}
return;
}
namespace Odd
{
int ans = 0;
int root1, root2;
void case1()
{
rep(down2, min_D)
{
int up1 = min_D - 1 - down2;
int up2 = up1, down1 = down2;
current_time++;
DP(root2, root1, down2, up2);
int foo = dp[root2][down2];
current_time++;
DP(root1, root2, down1, up1);
foo = 1ll * foo * dp[root1][down1] % mod;
ans += foo;
if(ans >= mod) ans -= mod;
}
debug(ans, '\n')
return;
}
void case2()
{
forn(down2, 1, min_D - 1)
{
int up2 = min_D - 1 - down2;
int up1 = min_D - down2;
int down1 = min_D - 1 - up1;
current_time++;
DP(root2, root1, down2, up2);
int foo = dp[root2][down2];
current_time++;
DP(root1, root2, down1, up1);
foo = 1ll * foo * dp[root1][down1] % mod;
ans += foo;
if(ans >= mod) ans -= mod;
}
debug(ans, '\n')
return;
}
void case3()
{
rep(down2, min_D)
{
int up1 = min_D - down2;
int up2 = up1 - 1;
int down1 = min_D - up1;
current_time++;
DP(root2 ,root1, down2, up2);
int foo = dp[root2][down2];
current_time++;
DP(root1, root2, down1, up1);
LL bar = dp[root1][down1];
if(down1 > 0)
{
current_time++;
DP(root1, root2, down1 - 1, up1);
bar += mod - dp[root1][down1 - 1];
}
if(up1 > 0)
{
current_time++;
DP(root1, root2, down1, up1 - 1);
bar += mod - dp[root1][down1];
}
foo = 1ll * foo * bar % mod;
ans += foo;
if(ans >= mod) ans -= mod;
}
debug(ans, '\n')
return;
}
void case4()
{
forn(down2, 1, min_D)
{
int up1 = min_D - down2;
int up2 = up1;
int down1 = min_D - 1 - up1;
current_time++;
DP(root2, root1, down2, up2);
LL foo = dp[root2][down2];
if(up2 > 0)
{
current_time++;
DP(root2, root1, down2, up2 - 1);
foo += mod - dp[root2][down2];
}
if(down2 > 0)
{
current_time++;
DP(root2, root1, down2 - 1, up2);
foo += mod - dp[root2][down2 - 1];
}
current_time++;
DP(root1, root2, down1, up1);
foo = foo * 1ll * dp[root1][down1] % mod;
ans += foo;
if(ans >= mod) ans -= mod;
}
debug(ans, '\n')
return;
}
void solve()
{
root1 = diameter_path[min_D - 1];
root2 = diameter_path[min_D];
case1();
case2();
case3();
case4();
ans += ans;
if(ans >= mod) ans -= mod;
printf("%d\n", ans);
return;
}
}
namespace Even
{
void solve()
{
int root = diameter_path[min_D];
int ans = 0;
forn(max_down, 0, min_D)
{
current_time++;
DP(root, 0, max_down, min_D - max_down);
ans += dp[root][max_down];
if(ans >= mod) ans -= mod;
}
printf("%d\n", ans);
return;
}
}
void ZI()
{
if(diameter_length == n - 1) Bamboo::solve();
else if(diameter_length & 1) Odd::solve();
else Even::solve();
return;
}
/*
Main
code
is
over
.
If
you
are
in
a
hurry
trying
to
hack
me
you
don't
need
to
read
the
part
left
.
Trust
me
.
It
is
useless
.
My
code
always
gets
a
failed
system
test
,
so
it
will
be
pretty
easy
for
you
to
hack
me
.
Just
find
a
test
case
and
hack
.
Wish
you
all
happy
hack
.
_____
/ \
| . . |
| |
| | |
| --- |
| \_/ |
\_____/
*/
#ifdef DEBUG
struct I{ int x; I(){} I(int y):x(y){} bool operator <(const I &a) const{ return x < a.x; }};
pair<I,LL> time_limit_exceeded;
const bool FLAG = 1;
static vector<I> wrong_answer;
I *RP=new I;
I FUCK=min(I{*RP}, I{0});
static int memory_limit_exceeded[10];
vi O(){cout<<FUCK.x<<endl; vi ert; int x=0;
x=(int)hypot(3.0, 4.0); ert.pb(x);
if(x&1)exit(0);
auto t=lower_bound(ALL(ert), 5);
static list<int> runtime_error_;
return ert;}
#endif // DEBUG
#define MEI int
#define ZI main
MEI ZI()
{
#undef MEI
#undef ZI
MEI();
ZI();
#define BA return
#define MEI 0
#define ZI ;
BA MEI ZI
#undef BA
#undef MEI
#undef ZI
}
Submission Info
Submission Time |
|
Task |
D - Oriented Tree |
User |
OMTWOCZWEIXVI |
Language |
C++14 (GCC 5.4.1) |
Score |
1800 |
Code Size |
7814 Byte |
Status |
AC |
Exec Time |
1200 ms |
Memory |
9344 KB |
Judge Result
Set Name |
Sample |
All |
Score / Max Score |
0 / 0 |
1800 / 1800 |
Status |
|
|
Set Name |
Test Cases |
Sample |
0_00.txt, 0_01.txt, 0_02.txt, 0_03.txt |
All |
0_00.txt, 0_01.txt, 0_02.txt, 0_03.txt, 1_00.txt, 1_01.txt, 1_02.txt, 1_03.txt, 1_04.txt, 1_05.txt, 1_06.txt, 1_07.txt, 1_08.txt, 1_09.txt, 1_10.txt, 1_11.txt, 1_12.txt, 1_13.txt, 1_14.txt, 1_15.txt, 1_16.txt, 1_17.txt, 1_18.txt, 1_19.txt, 1_20.txt, 1_21.txt, 1_22.txt, 1_23.txt, 1_24.txt, 1_25.txt, 1_26.txt, 1_27.txt, 1_28.txt |
Case Name |
Status |
Exec Time |
Memory |
0_00.txt |
AC |
2 ms |
2304 KB |
0_01.txt |
AC |
2 ms |
2304 KB |
0_02.txt |
AC |
2 ms |
2304 KB |
0_03.txt |
AC |
2 ms |
2432 KB |
1_00.txt |
AC |
2 ms |
2304 KB |
1_01.txt |
AC |
4 ms |
5376 KB |
1_02.txt |
AC |
3 ms |
5376 KB |
1_03.txt |
AC |
4 ms |
9088 KB |
1_04.txt |
AC |
4 ms |
9088 KB |
1_05.txt |
AC |
5 ms |
9088 KB |
1_06.txt |
AC |
18 ms |
9216 KB |
1_07.txt |
AC |
8 ms |
9088 KB |
1_08.txt |
AC |
28 ms |
9088 KB |
1_09.txt |
AC |
56 ms |
9088 KB |
1_10.txt |
AC |
24 ms |
9216 KB |
1_11.txt |
AC |
219 ms |
9216 KB |
1_12.txt |
AC |
84 ms |
9088 KB |
1_13.txt |
AC |
1200 ms |
9344 KB |
1_14.txt |
AC |
372 ms |
9344 KB |
1_15.txt |
AC |
639 ms |
9344 KB |
1_16.txt |
AC |
849 ms |
9344 KB |
1_17.txt |
AC |
5 ms |
9088 KB |
1_18.txt |
AC |
4 ms |
9088 KB |
1_19.txt |
AC |
4 ms |
9088 KB |
1_20.txt |
AC |
5 ms |
9088 KB |
1_21.txt |
AC |
4 ms |
9088 KB |
1_22.txt |
AC |
4 ms |
9088 KB |
1_23.txt |
AC |
4 ms |
9088 KB |
1_24.txt |
AC |
4 ms |
9088 KB |
1_25.txt |
AC |
4 ms |
9088 KB |
1_26.txt |
AC |
4 ms |
8960 KB |
1_27.txt |
AC |
4 ms |
9088 KB |
1_28.txt |
AC |
4 ms |
9088 KB |