Add 2nd test Link Cut Tree

Author: simonfallon

code/data-structures/__Test/LinkCutTree_Test.cpp renamed to code/data-structures/__Test/LinkCutTree_Test1.cpp

@@ -0,0 +1,124 @@
+// https://codeforces.com/gym/104713/problem/K
+#include <bits/stdc++.h>
+using namespace std;
+
+#define forn(i,n) for(int i=0; i<n; ++i)
+#define fi first
+#define se second
+#define el '\n'
+#define d(x) cout << #x << " : " << x<< el;
+
+typedef pair<int, int> ii;
+typedef long long ll;
+typedef vector<int> vi;
+typedef vector<ll> vll;
+typedef vector<ii> vii;
+
+struct Node { // Splay tree. Root's pp contains tree's parent.
+  Node *p = 0, *pp = 0, *c[2] = {0, 0};
+  bool flip = 0;
+  Node(){}
+  void fix() { forn(i, 2) if(c[i]) c[i]->p = this; }
+  inline int up() { return p ? p->c[1] == this : -1; }
+  void push() {
+    if (!flip) return;
+    flip = 0,  swap(c[0], c[1]);
+    forn(i, 2) if(c[i]) c[i]->flip ^= 1;
+  }
+  void rot(int i, int b) {
+    int h = i ^ b;
+    Node *x = c[i],  *y = b == 2 ? x : x->c[h],  *z = b ? y : x;
+    if ((y->p = p)) p->c[up()] = y;
+    c[i] = z->c[i^1];
+    if(b < 2) x->c[h] = y->c[h^1],  z->c[h^1] = b ? x : this;
+    y->c[i^1] = b ? this : x;
+    fix(),  x->fix(),  y->fix();
+    if(p) p->fix();
+    swap(pp, y->pp);
+  }
+  void splay() { // Splay *this up to the root. Finishes without flip set.
+    for(push(); p; ) {
+      if(p->p) p->p->push();
+      p->push(),  push();
+      int c1 = up(),  c2 = p->up();
+      if(c2 == -1) p->rot(c1, 2);
+      else p->p->rot(c2, c1 != c2);
+    }
+  }
+  Node* first() { return push(), c[0] ? c[0]->first() : (splay(), this); }
+}; // Return the MIN of the subtree rooted at this, splayed to the top.
+ 
+struct LinkCut {
+  vector<Node> node;
+  LinkCut(int n) : node(n) {}
+  Node* get(Node* u) { /// Move u to root aux tree. 
+    u->splay();
+    while (Node* pp = u->pp) {
+      pp->splay(),  u->pp = 0;
+      if(pp->c[1]) pp->c[1]->p = 0,  pp->c[1]->pp = pp;
+      pp->c[1] = u,  pp->fix(),  u = pp;
+    }
+    return u;  // Return the root of the root aux tree.
+  }
+  bool connected(int u, int v) { // are u, v in the same tree?
+    return get(&node[u])->first() == get(&node[v])->first(); 
+  }
+  void link(int u, int v) { // add an edge (u, v)
+    assert(!connected(u, v)),  makeRoot(&node[u]),  node[u].pp = &node[v];
+  }
+  void cut(int u, int v) { // remove an edge (u, v)
+    Node *x = &node[u], *top = &node[v];
+    makeRoot(top),  x->splay(),  assert(top == (x->pp ? : x->c[0]));
+    if(x->pp) x->pp = 0;
+    else x->c[0] = top->p = 0,  x->fix();
+  }  
+  void makeRoot(Node* u) { /// Move u to root of represented tree.
+    get(u),  u->splay();
+    if(u->c[0]) {
+      u->c[0]->p = 0;
+      u->c[0]->flip ^= 1;
+      u->c[0]->pp = u;
+      u->c[0] = 0,  u->fix();
+    }
+  }
+};
+
+ll gauss(int n){ return ll(n) * (n+1) / 2; }
+
+int main(){
+  ios_base::sync_with_stdio(0); cin.tie(0);
+  int n, m; cin >> n >> m;
+  vii edges(m);
+  forn(i, m){
+    int u, v; cin >> u >> v; 
+    edges[i] = {--u, --v};
+  }
+
+  vi R(m, m);
+  LinkCut lc(n);
+  int r = 0;
+  forn(l, m){
+    while(r < m && !lc.connected(edges[r].fi, edges[r].se)){
+      lc.link(edges[r].fi, edges[r].se),  ++r;
+    }
+    R[l] = r;
+    lc.cut(edges[l].fi, edges[l].se);
+  }
+  vll pR(m);  ll sum = 0;
+  forn(i, m) pR[i] = sum += (R[i] - i);
+
+  int q; cin >> q;
+  forn(_, q){
+    int l, r; cin >> l >> r; --l, --r;
+    if(R[l] > r+1) cout << gauss(r - l + 1) << el;
+    else{
+      int bl = l, br = r; // (1, 0)
+      while(bl+1 < br){
+        int bm = (bl + br) / 2;
+        if(R[bm] <= r+1) bl = bm;
+        else br = bm;
+      }
+      cout << pR[bl] - (l ? pR[l-1] : 0) + gauss(r - bl) << el;
+    }
+  }
+}