One Saturday afternoon Egor was playing his favorite RPG game. While discovering new lands and territories, he came across the following sign:
Egor is a passionate player, but he is an algorithmician as well. That’s why he instantly spotted four common letters in two words on the sign above — if we permute the letters “R”, “E”, “G”, “O” from the first word, we can obtain the letters “O”, “G”, “R”, “E”. Egor got inspired by the sign and right away he came up with a problem about permutations.
You are given a permutation of length n. You have to split it into some non-empty subsequences so that each element of the permutation belongs to exactly one subsequence. Each subsequence must be monotonic — that is, either increasing or decreasing.
Sequence is called to be a subsequence if it can be derived from permutation by deleting some (possibly none) elements without changing the order of the remaining elements.
The number of subsequences should be small enough — let f(n) be the minimum integer k such that every permutation of length n can be partitioned into at most k monotonic subsequences.
You need to split the permutation into at most f(n) monotonic subsequences.
Input
The first line contains one integer t (1≤t≤105) — the number of test cases.
You can only use t=1 in hacks.
Next, descriptions of t test cases come, each of them in the following format.
The first line of a single test case contains one integer n (1≤n≤105) — the length of the permutation. The second line contains n distinct integers ai (1≤ai≤n) — the permutation itself.
The sum of the values of n over all test cases doesn’t exceed 105.
Output
For each test case print the answer in the following format:
In the first line print k (1≤k≤f(n)) — the number of the subsequences in the partition. In the next k lines, print the descriptions of found subsequences. Each description should start with a number li (1≤li≤n) — the length of the corresponding subsequence, followed by li integers — the values of this subsequence in the order in which they occur in the permutation.
Each subsequence you output must be either increasing or decreasing.
In case there are multiple possible answers, print any of them.
Example
input
3 4 4 3 1 2 6 4 5 6 1 3 2 10 1 2 3 4 5 6 7 8 9 10
output
2 3 4 3 1 1 2 3 2 4 1 2 5 6 2 3 2 1 10 1 2 3 4 5 6 7 8 9 10
Note
In the example, we can split:
- [4,3,1,2] into [4,3,1], [2]
- [4,5,6,1,3,2] into [4,1], [5,6] and [3,2]
- [1,2,3,4,5,6,7,8,9,10] into [1,2,3,4,5,6,7,8,9,10]
Surely, there are many more answers possible.
Solution:
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 | #undef _GLIBCXX_DEBUG #include <bits/stdc++.h> using namespace std; string to_string(string s) { return '"' + s + '"' ; } string to_string( const char * s) { return to_string((string) s); } string to_string( bool b) { return (b ? "true" : "false" ); } template < typename A, typename B> string to_string(pair<A, B> p) { return "(" + to_string(p.first) + ", " + to_string(p.second) + ")" ; } template < typename A> string to_string(A v) { bool first = true ; string res = "{" ; for ( const auto &x : v) { if (!first) { res += ", " ; } first = false ; res += to_string(x); } res += "}" ; return res; } void debug_out() { cerr << endl; } template < typename Head, typename ... Tail> void debug_out(Head H, Tail... T) { cerr << " " << to_string(H); debug_out(T...); } #ifdef LOCAL #define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__) #else #define debug(...) 42 #endif int main() { ios::sync_with_stdio( false ); cin.tie(0); const int MAX = 100010; vector< int > pre(1, 0); for ( int i = 1; ( int ) pre.size() < MAX; i++) { for ( int j = 0; j < i + 1; j++) { pre.push_back(i); } } int tt; cin >> tt; while (tt--) { int n; cin >> n; vector< int > p(n); vector< int > pos(n, -1); for ( int i = 0; i < n; i++) { cin >> p[i]; p[i]--; pos[p[i]] = i; } vector< int > alive(n, 1); vector<vector< int >> res; vector< int > dp(n); vector< int > pr(n); int left = n; while (left > 0) { int found = 0; for ( int rot = 0; rot < 2; rot++) { vector<vector< int >> seq; vector< int > u; for ( int i = 0; i < n; i++) { if (!alive[i]) { continue ; } int x = p[i]; auto it = (rot == 0 ? lower_bound(u.begin(), u.end(), x, less< int >()) : lower_bound(u.begin(), u.end(), x, greater< int >())); dp[i] = ( int ) (it - u.begin()) + 1; pr[i] = (it == u.begin() ? -1 : u[dp[i] - 2]); if (it == u.end()) { seq.emplace_back(1, x); u.push_back(x); } else { seq[( int ) (it - u.begin())].push_back(x); *it = x; } } if (pre[left - ( int ) u.size()] + 1 <= pre[left]) { found = 1; vector< int > who; for ( int i = 0; i < n; i++) { if (alive[i] && dp[i] == ( int ) u.size()) { int j = i; while ( true ) { who.push_back(p[j]); if (pr[j] == -1) { break ; } j = pos[pr[j]]; } reverse(who.begin(), who.end()); assert (( int ) who.size() == ( int ) u.size()); break ; } } res.push_back(who); for ( int x : who) { alive[pos[x]] = 0; left--; } continue ; } vector< int > order(u.size()); iota(order.begin(), order.end(), 0); sort(order.begin(), order.end(), [&]( int i, int j) { return (seq[i].size() > seq[j].size()); }); // debug(seq); int sum = 0; for ( int i = 0; i < ( int ) u.size(); i++) { sum += ( int ) seq[order[i]].size(); if (pre[left - sum] + (i + 1) <= pre[left]) { found = 1; for ( int j = 0; j <= i; j++) { res.push_back(seq[order[j]]); for ( int x : seq[order[j]]) { alive[pos[x]] = 0; left--; } } break ; } } if (found) { break ; } } if (!found) debug(p); assert (found); } cout << ( int ) res.size() << '\n' ; for ( auto & v : res) { cout << ( int ) v.size(); for ( int i : v) { cout << " " << i + 1; } cout << '\n' ; } } return 0; } |