| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 71289 | Kmcode | Simurgh (IOI17_simurgh) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
//#include "books.h"
using namespace std;
//#include "simurgh.h"
int count_common_roads(const std::vector<int>& r);
#define MAX 512
struct UF{
int belong[MAX];
int sz[MAX];
int col[MAX];
UF(){
memset(belong,-1,sizeof(belong));
for(int i=0;i<MAX;i++)sz[i]=1;
}
inline int root(int b){
if(belong[b]==-1){
return b;
}
return belong[b]=root(belong[b]);
}
void merge(int a,int b){
a=root(a);
b=root(b);
if(a==b)return;
if(a>b)swap(a,b);
belong[a]=b;
sz[b]+=sz[a];
}
};
namespace solver{
const int white=503;
const int black=504;
vector<pair<int,int> > v;
vector<pair<int,int> > g[MAX];
int id[MAX];
int pr[MAX];
int dep[MAX];
UF uf;
vector<int> road;
vector<int> swa;
inline void dfs(int b,int pr2=-1,int d=0){
dep[b]=d;
for(auto go:g[b]){
if(go.first==pr2)continue;
dfs(go.first,b,d+1);
pr[go.first]=b;
id[go.first]=go.second;
}
}
int ini;
int ask(){
return count_common_roads(road);
}
void make_tree(){
UF uf2;
for(int i=0;i<v.size();i++){
swa.push_back(-1);
if(uf2.root(v[i].first)!=uf2.root(v[i].second)){
uf2.merge(v[i].first,v[i].second);
g[v[i].first].push_back(make_pair(v[i].second,i) );
g[v[i].second].push_back(make_pair(v[i].first,i) );
road.push_back(i);
swa[i]=road.size()-1;
}
}
ini=ask();
}
int query(int exp,int add){
road[swa[exp]]=add;
int z=ask();
road[swa[exp]]=exp;
return z-ini;
}
inline void check(int tree1,int tree2){
int r1=uf.root(tree1);
int r2=uf.root(tree2);
if(r1==r2)return;
if(r1==black||r1==white){
if(r2==black||r2==white){
return;
}
}
int ret=query(tree1,tree2);
if(ret==0){
uf.merge(tree1,tree2);
return;
}
if(ret>0){
uf.merge(black,tree2);
uf.merge(white,tree1);
return;
}
uf.merge(black,tree1);
uf.merge(white,tree2);
}
std::vector<int> find_roads(int n, std::vector<int> u1, std::vector<int> v1) {
for(int i=0;i<u1.size();i++){
v.push_back(make_pair(u1[i],v1[i]));
}
make_tree();
if(ini==n-1){
return road;
}
if(ini==0){
for(int i=0;i<road.size();i++){
uf.merge(road[i],white);
}
}
dfs(0);
for(int i=0;i<v.size();i++){
if(dep[v[i].first]>dep[v[i].second])swap(v[i].first,v[i].second);
if(pr[v[i].second]==v[i].first)continue;
int a=v[i].first;
int b=v[i].second;
while(a!=b){
if(dep[a]<dep[b]){
check(id[b],i);
b=pr[b];
}
else{
check(id[a],i);
a=pr[a];
}
}
}
vector<int> ans;
UF uf2;
for(int i=0;i<v.size();i++){
if(uf.root(i)==black){
ans.push_back(i);
uf2.merge(v[i].first,v[i].second);
}
}
for(int i=0;i<road.size();i++){
int a=v[road[i]].first;
int b=v[road[i]].second;
if(uf2.root(a)!=uf2.root(b)){
uf2.merge(a,b);
ans.push_back(road[i]);
}
}
return ans;
}
}
std::vector<int> find_roads(int n, std::vector<int> u, std::vector<int> v) {
return solver::find_roads(n,u,v);
}
static int MAXQ = 30000;
static int n, m, q = 0;
static vector<int> u, v;
static vector<bool> goal;
static void wrong_answer() {
printf("NO\n");
exit(0);
}
static bool is_valid(const vector<int>& r) {
if(int(r.size()) != n - 1)
return false;
for(int i = 0; i < n - 1; i++)
if (r[i] < 0 || r[i] >= m)
return false;
return true;
}
static int _count_common_roads_internal(const vector<int>& r) {
if(!is_valid(r))
wrong_answer();
int common = 0;
for(int i = 0; i < n - 1; i++) {
bool is_common = goal[r[i]];
if (is_common)
common++;
}
return common;
}
int count_common_roads(const vector<int>& r) {
q++;
if(q > MAXQ)
wrong_answer();
return _count_common_roads_internal(r);
}
int main() {
assert(2 == scanf("%d %d", &n, &m));
u.resize(m);
v.resize(m);
for(int i = 0; i < m; i++)
assert(2 == scanf("%d %d", &u[i], &v[i]));
goal.resize(m, false);
for(int i = 0; i < n - 1; i++) {
int id;
assert(1 == scanf("%d", &id));
goal[id] = true;
}
vector<int> res = find_roads(n, u, v);
if(_count_common_roads_internal(res) != n - 1)
wrong_answer();
printf("YES\n");
return 0;
}