File size: 4,583 Bytes
1fd0050 | 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 | #include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T;
cin >> T;
for (int t = 0; t < T; ++t) {
int n;
cin >> n;
vector<int> p(n + 1);
for (int i = 1; i <= n; ++i) {
cin >> p[i];
}
vector<pair<int, int>> edge_list(n);
vector<vector<pair<int, int>>> edge_adj(n + 1);
for (int i = 1; i <= n - 1; ++i) {
int u, v;
cin >> u >> v;
edge_list[i] = {u, v};
edge_adj[u].emplace_back(v, i);
edge_adj[v].emplace_back(u, i);
}
// Build tree_adj for dist
vector<vector<int>> tree_adj(n + 1);
for (int i = 1; i <= n - 1; ++i) {
int u = edge_list[i].first, v = edge_list[i].second;
tree_adj[u].push_back(v);
tree_adj[v].push_back(u);
}
// Precompute all pairs dist
vector<vector<int>> dist(n + 1, vector<int>(n + 1, -1));
for (int s = 1; s <= n; ++s) {
vector<int> d(n + 1, -1);
d[s] = 0;
queue<int> q;
q.push(s);
while (!q.empty()) {
int u = q.front();
q.pop();
for (int v : tree_adj[u]) {
if (d[v] == -1) {
d[v] = d[u] + 1;
q.push(v);
}
}
}
for (int i = 1; i <= n; ++i) {
dist[s][i] = d[i];
}
}
// Current label
vector<int> label = p;
// Operations
vector<vector<int>> operations;
bool is_sorted = false;
while (!is_sorted) {
bool check_sorted = true;
for (int i = 1; i <= n; ++i) {
if (label[i] != i) {
check_sorted = false;
break;
}
}
is_sorted = check_sorted;
if (is_sorted) break;
// Collect prio and norm
vector<int> prio, norm;
for (int eid = 1; eid <= n - 1; ++eid) {
int u = edge_list[eid].first;
int v = edge_list[eid].second;
int lu = label[u], lv = label[v];
int tu = lu, tv = lv;
int old_du = dist[u][tu];
int new_du = dist[v][tu];
int d1 = new_du - old_du;
int old_dv = dist[v][tv];
int new_dv = dist[u][tv];
int d2 = new_dv - old_dv;
int del = d1 + d2;
if (del <= 0) {
if (del == -2) {
prio.push_back(eid);
} else { // del == 0
bool can = false;
if (d1 == 1) {
if (old_du == 0) can = true;
} else if (d2 == 1) {
if (old_dv == 0) can = true;
}
if (can) {
norm.push_back(eid);
}
}
}
}
// Build selected
vector<int> selected;
vector<bool> used(n + 1, false);
auto add_if_possible = [&](int eid) -> bool {
int u = edge_list[eid].first;
int v = edge_list[eid].second;
if (!used[u] && !used[v]) {
selected.push_back(eid);
used[u] = true;
used[v] = true;
return true;
}
return false;
};
for (int eid : prio) {
add_if_possible(eid);
}
for (int eid : norm) {
add_if_possible(eid);
}
if (selected.empty()) {
// Should not happen
break;
}
// Record
operations.push_back(selected);
// Perform swaps
for (int eid : selected) {
int u = edge_list[eid].first;
int v = edge_list[eid].second;
swap(label[u], label[v]);
}
}
// Output
cout << operations.size() << '\n';
for (auto& op : operations) {
cout << op.size();
for (int e : op) {
cout << " " << e;
}
cout << '\n';
}
}
return 0;
} |