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hackercup / 2021 /finals /table_flipping.cpp
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2021 Problems
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#include <algorithm>
#include <cstring>
#include <iostream>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
const int LIM = 300003;
using pii = pair<int, int>;
#define x first
#define y second
struct Compressor {
int N;
vector<pii> V;
Compressor() {}
Compressor(vector<pii> _V) {
V = _V;
comp();
}
void insert(pii v) {
V.push_back(v);
}
void comp() {
sort(V.begin(), V.end());
N = unique(V.begin(), V.end()) - V.begin();
V.resize(N);
}
int get(pii v) {
return lower_bound(V.begin(), V.end(), v) - V.begin();
}
};
const int TLIM = 2100000;
const int ZERO_VAL = 0;
const int ZERO_LAZY = 0;
struct MaxRangeSegTree {
static void update_value(int &a, int v, int r1, int r2) { a += v; }
static void update_lazy(int &a, int v, int r1, int r2) { a += v; }
static int join_values(int v1, int v2) { return max(v1, v2); }
int N, sz;
int tree[TLIM];
int lazy[TLIM];
MaxRangeSegTree() {}
MaxRangeSegTree(int _N) { init(_N); }
void init(int _N) {
N = _N;
for (sz = 1; sz < N; sz <<= 1)
;
clear();
}
void clear() {
for (int i = 0; i < (sz << 1); i++) {
tree[i] = ZERO_VAL;
lazy[i] = ZERO_LAZY;
}
}
void propagate(int i, int r1, int r2) {
int v = lazy[i];
lazy[i] = ZERO_LAZY;
update_value(tree[i], v, r1, r2);
if (i < sz) {
int m = (r1 + r2) >> 1, c1 = i << 1, c2 = c1 + 1;
update_lazy(lazy[c1], v, r1, m);
update_lazy(lazy[c2], v, m + 1, r2);
}
}
void comp(int i) {
int c1 = i << 1, c2 = c1 + 1;
tree[i] = join_values(tree[c1], tree[c2]);
}
int query(int a, int b, int i = 1, int r1 = 0, int r2 = -1) {
if (r2 < 0) {
a = max(a, 0);
b = min(b, sz - 1);
if (a > b) {
return ZERO_VAL;
}
r2 = sz - 1;
}
propagate(i, r1, r2);
if (a <= r1 && r2 <= b) {
return tree[i];
}
int m = (r1 + r2) >> 1, c = i << 1;
int res = ZERO_VAL;
if (a <= m) {
res = join_values(res, query(a, b, c, r1, m));
}
if (b > m) {
res = join_values(res, query(a, b, c + 1, m + 1, r2));
}
return res;
}
void update(int a, int b, int v, int i = 1, int r1 = 0, int r2 = -1) {
if (r2 < 0) {
a = max(a, 0);
b = min(b, sz - 1);
if (a > b) {
return;
}
r2 = sz - 1;
}
if (r2 < 0) {
r2 = sz - 1;
}
propagate(i, r1, r2);
if (a <= r1 && r2 <= b) {
update_lazy(lazy[i], v, r1, r2);
propagate(i, r1, r2);
return;
}
int m = (r1 + r2) >> 1, c = i << 1;
if (a <= m) {
update(a, b, v, c, r1, m);
}
if (b > m) {
update(a, b, v, c + 1, m + 1, r2);
}
propagate(c, r1, m);
propagate(c + 1, m + 1, r2);
comp(i);
}
};
const pii NONE{-1, -1};
struct MaxElemSegTree {
pii join_values(pii v1, pii v2) { return max(v1, v2); }
int N, sz;
vector<pii> tree;
MaxElemSegTree() {}
MaxElemSegTree(int _N) { init(_N); }
void init(int _N) {
N = _N;
for (sz = 1; sz < N; sz <<= 1)
;
clear();
}
void clear() {
tree.clear();
tree.resize(sz << 1, NONE);
}
void comp(int i) {
int c1 = i << 1, c2 = c1 + 1;
tree[i] = join_values(tree[c1], tree[c2]);
}
pii query(int a, int b, int i = 1, int r1 = 0, int r2 = -1) {
if (r2 < 0) {
a = max(a, 0);
b = min(b, sz - 1);
if (a > b) {
return NONE;
}
r2 = sz - 1;
}
if (a <= r1 && r2 <= b) {
return tree[i];
}
int m = (r1 + r2) >> 1, c = i << 1;
pii res = NONE;
if (a <= m) {
res = join_values(res, query(a, b, c, r1, m));
}
if (b > m) {
res = join_values(res, query(a, b, c + 1, m + 1, r2));
}
return res;
}
void update_one(int i, pii p) {
i += sz;
tree[i] = p;
while (i > 1) {
i >>= 1;
comp(i);
}
}
};
struct NestedSegTree {
int N, sz;
bool has_init_keys;
vector<int> keys[TLIM];
MaxElemSegTree T[TLIM];
NestedSegTree() {}
NestedSegTree(int _N) { init(_N); }
void init(int _N) {
N = _N;
for (sz = 1; sz < N; sz <<= 1)
;
has_init_keys = false;
}
void init_keys() {
for (int i = sz; i < sz + N; i++) {
auto &k = keys[i];
sort(k.begin(), k.end());
k.resize(unique(k.begin(), k.end()) - k.begin());
T[i].init(k.size());
}
for (int i = sz - 1; i >= 1; i--) {
auto &k = keys[i], &c1 = keys[i << 1], &c2 = keys[(i << 1) + 1];
int a = 0, b = 0;
while (a < c1.size() || b < c2.size()) {
if (a < c1.size() && b < c2.size() && c1[a] == c2[b]) {
k.push_back(c1[a++]);
b++;
} else if (b == c2.size() || (a < c1.size() && c1[a] < c2[b])) {
k.push_back(c1[a++]);
} else {
k.push_back(c2[b++]);
}
}
T[i].init(k.size());
}
has_init_keys = true;
}
pii query_max_up_to_k(int a, int b, int k, int i = 1, int r1 = 0, int r2 = -1) {
if (r2 < 0) {
a = max(a, 0);
b = min(b, sz - 1);
if (a > b) {
return NONE;
}
r2 = sz - 1;
}
if (a <= r1 && r2 <= b) {
k = lower_bound(keys[i].begin(), keys[i].end(), k + 1) - keys[i].begin() - 1;
return T[i].query(0, k);
}
int m = (r1 + r2) >> 1, c = i << 1;
pii res = NONE;
if (a <= m) {
res = max(res, query_max_up_to_k(a, b, k, c, r1, m));
}
if (b > m) {
res = max(res, query_max_up_to_k(a, b, k, c + 1, m + 1, r2));
}
return res;
}
void update_one(int i, int k, pii p) {
i += sz;
if (!has_init_keys) {
keys[i].push_back(k);
return;
}
while (i >= 1) {
T[i].update_one(
lower_bound(keys[i].begin(), keys[i].end(), k) - keys[i].begin(), p
);
i >>= 1;
}
}
};
int N;
pair<pii, pii> A[LIM], B[LIM];
int Axx[LIM], Axy[LIM];
int lowerX[3 * LIM], lowerY[3 * LIM];
bool visit[LIM];
NestedSegTree STX, STY;
void update_A_rect(int i, bool ins) {
STX.update_one(A[i].x.x, Axy[i], ins ? make_pair(A[i].y.y, i) : NONE);
STX.update_one(A[i].y.x, Axy[i], ins ? make_pair(A[i].y.y, i) : NONE);
STY.update_one(A[i].x.y, Axx[i], ins ? make_pair(A[i].y.x, i) : NONE);
STY.update_one(A[i].y.y, Axx[i], ins ? make_pair(A[i].y.x, i) : NONE);
}
int get_A_rect_for_B_rect(int i) {
pii p = STX.query_max_up_to_k(B[i].x.x, B[i].y.x, B[i].y.y);
if (p.x >= B[i].x.y) {
return p.y;
}
p = STY.query_max_up_to_k(B[i].x.y, B[i].y.y, B[i].y.x);
if (p.x >= B[i].x.x) {
return p.y;
}
return -1;
}
bool rec(int i) {
visit[i] = true;
for (;;) {
int j = get_A_rect_for_B_rect(i);
if (j < 0) {
break;
}
if (visit[j]) {
return true;
}
if (rec(j)) {
return true;
}
}
update_A_rect(i, 0);
return false;
}
bool solve() {
Compressor cx, cy;
// Input, and compute flipped rectangles.
cin >> N;
for (int i = 0; i < N; i++) {
char c;
cin >> A[i].x.x >> A[i].x.y >> A[i].y.x >> A[i].y.y >> c;
B[i] = A[i];
switch (c) {
case 'U': B[i].x.y += A[i].y.y; break;
case 'D': B[i].x.y -= A[i].y.y; break;
case 'L': B[i].x.x -= A[i].y.x; break;
case 'R': B[i].x.x += A[i].y.x; break;
}
A[i].y.x += A[i].x.x;
A[i].y.y += A[i].x.y;
B[i].y.x += B[i].x.x;
B[i].y.y += B[i].x.y;
cx.insert({A[i].x.x, i});
cx.insert({A[i].y.x, i}),
cx.insert({B[i].x.x, i});
cx.insert({B[i].y.x, i});
cy.insert({A[i].x.y, i});
cy.insert({A[i].y.y, i});
cy.insert({B[i].x.y, i});
cy.insert({B[i].y.y, i});
}
// Compress coordinates.
cx.comp(), cy.comp();
auto V = cx.V;
for (int i = 0; i < V.size(); i++) {
lowerX[i] = (i == 0 || V[i - 1].x != V[i].x) ? i : lowerX[i - 1];
}
V = cy.V;
for (int i = 0; i < V.size(); i++) {
lowerY[i] = (i == 0 || V[i - 1].x != V[i].x) ? i : lowerY[i - 1];
}
for (int i = 0; i < N; i++) {
A[i].x.x = cx.get({A[i].x.x, i});
A[i].x.y = cy.get({A[i].x.y, i}),
A[i].y.x = cx.get({A[i].y.x, i});
A[i].y.y = cy.get({A[i].y.y, i});
B[i].x.x = cx.get({B[i].x.x, i});
B[i].x.y = cy.get({B[i].x.y, i}),
B[i].y.x = cx.get({B[i].y.x, i});
B[i].y.y = cy.get({B[i].y.y, i});
// Remember exact (unique) lower coordinates.
Axx[i] = A[i].x.x, Axy[i] = A[i].x.y;
// Round coordinates up to value boundaries (with exclusive upper
// coordinates).
A[i].x.x = lowerX[A[i].x.x];
B[i].x.x = lowerX[B[i].x.x];
A[i].x.y = lowerY[A[i].x.y];
B[i].x.y = lowerY[B[i].x.y];
A[i].y.x = lowerX[A[i].y.x] - 1;
B[i].y.x = lowerX[B[i].y.x] - 1;
A[i].y.y = lowerY[A[i].y.y] - 1;
B[i].y.y = lowerY[B[i].y.y] - 1;
}
// Check for any overlap between final tables via line sweep.
vector<tuple<int, int, int, int>> E;
for (int i = 0; i < N; i++) {
E.emplace_back(B[i].x.y, 1, B[i].x.x, B[i].y.x);
E.emplace_back(B[i].y.y + 1, -1, B[i].x.x, B[i].y.x);
}
sort(E.begin(), E.end());
MaxRangeSegTree ST(cx.V.size());
for (auto e : E) {
ST.update(get<2>(e), get<3>(e), get<1>(e));
if (ST.query(0, cx.V.size() - 1) > 1) {
return false;
}
}
// Initialize segment trees of initial tables, over x and y coordinates.
STX = NestedSegTree(cx.V.size());
STY = NestedSegTree(cy.V.size());
for (int j : {0, 1}) {
if (j) { // Initialize keys second time around.
STX.init_keys();
STY.init_keys();
}
for (int i = 0; i < N; i++) {
// Set up keys first time around, then perform actual updates.
update_A_rect(i, 1);
}
}
// Search for cycles via DFS.
memset(visit, 0, sizeof visit);
for (int i = 0; i < N; i++) {
if (!visit[i]) {
if (rec(i)) {
return false; // Cycle found.
}
}
}
return true;
}
int main() {
int T;
cin >> T;
for (int t = 1; t <= T; t++) {
cout << "Case #" << t << ": " << (solve() ? "YES" : "NO") << endl;
}
return 0;
}