File size: 3,220 Bytes
f96d8dd |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 |
// Somebody Else's Problem
// Solution by Jacob Plachta
#include <algorithm>
#include <functional>
#include <numeric>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <complex>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <sstream>
using namespace std;
#define LL long long
#define LD long double
#define PR pair<int,int>
#define Fox(i,n) for (i=0; i<n; i++)
#define Fox1(i,n) for (i=1; i<=n; i++)
#define FoxI(i,a,b) for (i=a; i<=b; i++)
#define FoxR(i,n) for (i=(n)-1; i>=0; i--)
#define FoxR1(i,n) for (i=n; i>0; i--)
#define FoxRI(i,a,b) for (i=b; i>=a; i--)
#define Foxen(i,s) for (auto i:s)
#define Min(a,b) a=min(a,b)
#define Max(a,b) a=max(a,b)
#define Sz(s) int((s).size())
#define All(s) (s).begin(),(s).end()
#define Fill(s,v) memset(s,v,sizeof(s))
#define pb push_back
#define mp make_pair
#define x first
#define y second
template<typename T> T Abs(T x) { return(x < 0 ? -x : x); }
template<typename T> T Sqr(T x) { return(x * x); }
string plural(string s) { return(Sz(s) && s[Sz(s) - 1] == 'x' ? s + "en" : s + "s"); }
const int INF = (int)1e9;
const LD EPS = 1e-12;
const LD PI = acos(-1.0);
#define GETCHAR getchar_unlocked
bool Read(int& x) {
char c, r = 0, n = 0;
x = 0;
for (;;) {
c = GETCHAR();
if ((c < 0) && (!r))
return(0);
if ((c == '-') && (!r))
n = 1;
else if ((c >= '0') && (c <= '9'))
x = x * 10 + c - '0', r = 1;
else if (r)
break;
}
if (n)
x = -x;
return(1);
}
#define MOD 1000000007
#define LIM 1000001
int N, ans;
vector<int> ch[LIM];
int dyn1[LIM]; // max. len. of downward i -> leaf
int dyn2[LIM]; // max. len. of downward root -> leaf outside i's subtree
int dyn3[LIM]; // max. disjoint len. of downward root -> leaf plus other path ongoing from i's parent
void rec1(int i)
{
// recurse, and compute dyn1[i]
dyn1[i] = 0;
Foxen(c, ch[i])
{
rec1(c);
Max(dyn1[i], dyn1[c] + 1);
}
}
void rec2(int i, int d)
{
// compute answer for i
ans = ans * (LL)max(dyn1[i] + dyn2[i] + (!i ? 0 : 1), dyn3[i]) % MOD;
// compute max 2 (dyn1[c] + 1, c) pairs
PR m1, m2;
m1 = m2 = mp(0, -1);
Foxen(c, ch[i])
{
PR p = mp(dyn1[c] + 1, c);
if (p > m1)
m2 = m1, m1 = p;
else if (p > m2)
m2 = p;
}
// compute dyn2[c] and dyn3[c], and recurse
Foxen(c, ch[i])
{
int m = (m1.y == c ? m2 : m1).x;
dyn2[c] = max(d + m, dyn2[i]);
dyn3[c] = max(dyn3[i] + 1, dyn2[i] + m + 1 + (!i ? 0 : 1));
rec2(c, d + 1);
}
}
int ProcessCase()
{
int i, j;
// input
Read(N);
Fox1(i, N - 1)
{
Read(j), j--;
ch[j].pb(i);
}
// DP
ans = 1;
rec1(0);
rec2(0, 0);
// reset
Fox(i, N)
ch[i].clear();
return(ans);
}
int main()
{
int T, t;
Read(T);
Fox1(t, T)
printf("Case #%d: %d\n", t, ProcessCase());
return(0);
} |