File size: 5,172 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 | #include <bits/stdc++.h>
using namespace std;
struct FastScanner {
static constexpr size_t BUFSIZE = 1 << 20;
int idx = 0, size = 0;
char buf[BUFSIZE];
inline char readChar() {
if (idx >= size) {
size = (int)fread(buf, 1, BUFSIZE, stdin);
idx = 0;
if (size == 0) return 0;
}
return buf[idx++];
}
template <class T>
bool readInt(T &out) {
char c;
do {
c = readChar();
if (!c) return false;
} while (c <= ' ');
bool neg = false;
if (c == '-') {
neg = true;
c = readChar();
}
T val = 0;
while (c > ' ') {
val = val * 10 + (c - '0');
c = readChar();
}
out = neg ? -val : val;
return true;
}
};
struct FastOutput {
static constexpr size_t BUFSIZE = 1 << 20;
char buf[BUFSIZE];
size_t idx = 0;
~FastOutput() { flush(); }
inline void flush() {
if (idx) {
fwrite(buf, 1, idx, stdout);
idx = 0;
}
}
inline void pushChar(char c) {
if (idx >= BUFSIZE) flush();
buf[idx++] = c;
}
inline void writeInt(long long x) {
if (x == 0) {
pushChar('0');
return;
}
if (x < 0) {
pushChar('-');
x = -x;
}
char s[24];
int n = 0;
while (x) {
s[n++] = char('0' + (x % 10));
x /= 10;
}
while (n--) pushChar(s[n]);
}
inline void writeStr(const char* s) {
while (*s) pushChar(*s++);
}
inline void writeNewline() { pushChar('\n'); }
};
struct AdjEdge {
int to, id;
};
int main() {
FastScanner fs;
FastOutput fo;
int T;
if (!fs.readInt(T)) return 0;
while (T--) {
int n;
fs.readInt(n);
vector<int> p(n + 1), pos(n + 1);
for (int i = 1; i <= n; i++) {
fs.readInt(p[i]);
pos[p[i]] = i;
}
vector<vector<AdjEdge>> adj(n + 1);
adj.assign(n + 1, {});
for (int i = 1; i <= n - 1; i++) {
int u, v;
fs.readInt(u);
fs.readInt(v);
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
vector<char> active(n + 1, 1);
vector<int> deg(n + 1, 0);
deque<int> dq;
for (int i = 1; i <= n; i++) {
deg[i] = (int)adj[i].size();
}
for (int i = 1; i <= n; i++) {
if (deg[i] <= 1) dq.push_back(i);
}
vector<int> ops;
ops.reserve(n * n);
vector<char> vis(n + 1, 0);
vector<int> parent(n + 1, 0), parentE(n + 1, 0);
vector<int> st;
st.reserve(n);
auto doSwap = [&](int a, int b, int eid) {
ops.push_back(eid);
int pa = p[a], pb = p[b];
p[a] = pb; p[b] = pa;
pos[pa] = b;
pos[pb] = a;
};
int activeCount = n;
while (activeCount > 1) {
int v = -1;
while (!dq.empty()) {
int x = dq.front();
dq.pop_front();
if (active[x] && deg[x] == 1) {
v = x;
break;
}
}
if (v == -1) break; // should not happen
int start = pos[v];
if (start != v) {
fill(vis.begin(), vis.end(), 0);
st.clear();
st.push_back(v);
vis[v] = 1;
parent[v] = 0;
parentE[v] = 0;
while (!st.empty()) {
int cur = st.back();
st.pop_back();
if (cur == start) break;
for (const auto &e : adj[cur]) {
int to = e.to;
if (!active[to] || vis[to]) continue;
vis[to] = 1;
parent[to] = cur;
parentE[to] = e.id;
st.push_back(to);
}
}
int cur = start;
while (cur != v) {
int nxt = parent[cur];
int eid = parentE[cur];
doSwap(cur, nxt, eid);
cur = nxt;
}
}
active[v] = 0;
activeCount--;
int neigh = 0;
for (const auto &e : adj[v]) {
if (active[e.to]) {
neigh = e.to;
break;
}
}
if (neigh) {
deg[neigh]--;
if (deg[neigh] == 1 && activeCount > 1) dq.push_back(neigh);
}
deg[v] = 0;
}
fo.writeInt((long long)ops.size());
fo.writeNewline();
for (int eid : ops) {
fo.writeInt(1);
fo.pushChar(' ');
fo.writeInt(eid);
fo.writeNewline();
}
}
fo.flush();
return 0;
} |