using namespace std;
// 17.4.1.2 Headers
// C
#ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#endif
// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#endif
#define ll long long
#define ld long double
#define ar array
typedef priority_queue<int> pqi;
typedef pair<int,int> pii;
typedef vector<pair<int,int>> vpii;
typedef vector<int> vi;
ll gcd(ll a, ll b) {
if (!a || !b)
return a | b;
unsigned shift = __builtin_ctz(a | b);
a >>= __builtin_ctz(a);
do {
b >>= __builtin_ctz(b);
if (a > b)
swap(a, b);
b -= a;
} while (b);
return a << shift;
}
ll lcm(ll a, ll b){
return (ll)a*b/gcd(a,b);
}
#define vt vector
#define pb push_back
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
#define F_OR(i, a, b, s) for (int i=(a); (s)>0?i<(b):i>(b); i+=(s))
#define FORR1(e) F_OR(i, 0, e, 1)
#define FORR2(i, e) F_OR(i, 0, e, 1)
#define FORR3(i, b, e) F_OR(i, b, e, 1)
#define FORR4(i, b, e, s) F_OR(i, b, e, s)
#define GET5(a, b, c, d, e, ...) e
#define F_ORC(...) GET5(__VA_ARGS__, FORR4, FORR3, FORR2, FORR1)
#define FOR(...) F_ORC(__VA_ARGS__)(__VA_ARGS__)
#define EACH(x, a) for (auto& x: a)
const int INF = 2*((1<<30)-1)+1;
int lsb(int i){
return i&-i;
}
template<class T> bool umin(T& a, const T& b) {
return b<a?a=b, 1:0;
}
template<class T> bool umax(T& a, const T& b) {
return a<b?a=b, 1:0;
}
int binarySearch(vi arr, int p, int r, int num) {
if (p <= r) {
int mid = (p + r)/2;
if (arr[mid] == num)
return mid ;
if (arr[mid] > num)
return binarySearch(arr, p, mid-1, num);
if (arr[mid] > num)
return binarySearch(arr, mid+1, r, num);
}
return -1;
}
ll FIRSTTRUE(function<bool(ll)> f, ll lb, ll rb) {
while(lb<rb) {
ll mb=(lb+rb)/2;
f(mb)?rb=mb:lb=mb+1;
}
return lb;
}
ll LASTTRUE(function<bool(ll)> f, ll lb, ll rb) {
while(lb<rb) {
ll mb=(lb+rb+1)/2;
f(mb)?lb=mb:rb=mb-1;
}
return lb;
}
template<class A> void read(vt<A>& v);
template<class A, size_t S> void read(ar<A, S>& a);
template<class T> void read(T& x) {
cin >> x;
}
void read(double& d) {
string t;
read(t);
d=stod(t);
}
void read(long double& d) {
string t;
read(t);
d=stold(t);
}
template<class H, class... T> void read(H& h, T&... t) {
read(h);
read(t...);
}
template<class A> void read(vt<A>& x) {
EACH(a, x)
read(a);
}
template<class A, size_t S> void read(array<A, S>& x) {
EACH(a, x)
read(a);
}
string to_string(char c) {
return string(1, c);
}
string to_string(bool b) {
return b?"true":"false";
}
string to_string(const char* s) {
return string(s);
}
string to_string(string s) {
return s;
}
string to_string(vt<bool> v) {
string res;
FOR(sz(v))
res+=char('0'+v[i]);
return res;
}
template<size_t S> string to_string(bitset<S> b) {
string res;
FOR(S)
res+=char('0'+b[i]);
return res;
}
template<class T> string to_string(T v) {
bool f=1;
string res;
EACH(x, v) {
if(!f)
res+=' ';
f=0;
res+=to_string(x);
}
return res;
}
template<class A> void write(A x) {
cout << to_string(x);
}
template<class H, class... T> void write(const H& h, const T&... t) {
write(h);
write(t...);
}
void print() {
write("\n");
}
template<class H, class... T> void print(const H& h, const T&... t) {
write(h);
if(sizeof...(t))
write(' ');
print(t...);
}
void DBG() {
cerr << "]" << endl;
}
template<class H, class... T> void DBG(H h, T... t) {
cerr << to_string(h);
if(sizeof...(t))
cerr << ", ";
DBG(t...);
}
#ifdef _DEBUG
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif
template<class T> void offset(ll o, T& x) {
x+=o;
}
template<class T> void offset(ll o, vt<T>& x) {
EACH(a, x)
offset(o, a);
}
template<class T, size_t S> void offset(ll o, ar<T, S>& x) {
EACH(a, x)
offset(o, a);
}
mt19937 mt_rng(chrono::steady_clock::now().time_since_epoch().count());
ll randint(ll a, ll b) {
return uniform_int_distribution<ll>(a, b)(mt_rng);
}
template<class T, class U> void vti(vt<T> &v, U x, size_t n) {
v=vt<T>(n, x);
}
template<class T, class U> void vti(vt<T> &v, U x, size_t n, size_t m...) {
v=vt<T>(n);
EACH(a, v)
vti(a, x, m);
}
const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};
const int mxN=5e5+1, M=1e9+7;
int n, m, p[mxN];
int find(int x) {
return x^p[x]?p[x]=find(p[x]):x;
}
bool join(int x, int y) {
if((x=find(x))==(y=find(y)))
return 0;
p[x]=y;
return 1;
}
vi ans;
vt<vi> adjlist;
queue<int> nodelist;
vt<bool> visited;
vt<vi> weightlist;
void bfs(int start){
ans[start] = 0;
nodelist.push(start);
while(!nodelist.empty()){
int node = nodelist.front();
visited[node] = true;
for(int e : adjlist[node]){
if(!visited[e]){
nodelist.push(e);
ans[e] = ans[node]+1;
visited[e] = true;
}
}
nodelist.pop();
}
}
int pmst(int start){
int n = adjlist.size();
visited.resize(n);
FORR1(n){
visited[i] = false;
}
visited[start] = true;
priority_queue<pair<int,pair<int,int>>,vt<pair<int,pair<int,int>>>,greater<pair<int,pair<int,int>>>> pq;
for(int i = 0; i < adjlist[start].size(); i++){
pq.push(make_pair(weightlist[start][i],make_pair(start,adjlist[start][i])));
}
stack<int> nodes;
int ans = 0;
nodes.push(start);
while(nodes.size()!=n){
pair<int,pair<int,int>> trip = pq.top();
pq.pop();
int w = trip.first;
int a = trip.second.first;
int b = trip.second.second;
if(visited[a]&&visited[b]){
continue;
}
visited[b] = true;
nodes.push(b);
ans+=w;
FORR1(adjlist[b].size()){
if(!visited[adjlist[b][i]]){
pq.push(make_pair(weightlist[b][i],make_pair(b,adjlist[b][i])));
}
}
}
return ans;
}
void dfs(int node){
}
void update(vi arr, int index, int val){
int n = arr.size();
int x = index+(1<<lsb(index+1));
int og = arr[index];
arr[index] = val;
while(x<n){
arr[x]/=og;
arr[x]*=val;
x = x + (1<<lsb(x+1));
}
}
int query(vi arr, int val){
int ans = 0;
val++;
while(val!=0){
ans*=arr[val-1];
val-(1<<lsb(val));
}
return ans;
}
string reverse(string s){
string str = "";
for(int i = s.length()-1; i >=0; i--){
str+=s.substr(i,1);
}
return str;
}
string leximax(string a, string b){
if(a>b){
return a;
}
return b;
}
string leximin(string a, string b){
if(a>b){
return b;
}
return a;
}
bool gemacht(int num, vi p){
}
bool issorted(vi arr){
int b = true;
int n = arr.size();
for(int i = 1; i < n; i++){
if(arr[i]<arr[i-1]){
b = false;
break;
}
}
return b;
}
bool continuous(vi arr){
int n = arr.size();
bool bol = true;
for(int i = 1; i < n; i++){
if(arr[i]-arr[i-1]!=1){
bol = false;
break;
}
}
return bol;
}
vi arr;
vi Max;
vi Min;
vi Sizze;
int Maxs;
int Comps;
int get(int node){
return arr[node] = (arr[node] == node ? node : get(arr[node]));
}
void unn(int node1, int node2){
if(get(node1)!=get(node2)){
Sizze[get(node1)]+=Sizze[get(node2)];
Maxs = max(Maxs,Sizze[get(node1)]);
Comps--;
arr[get(node2)] = get(node1);
}
}
int beginn;
int endd;
void query(){
write("? ",(beginn+endd)/2);
fflush(stdout);
read(ans);
}
void solve() {
int n;
read(n);
map<string,string> Map;
vt<string> arr(n);
FORR1(n){
string s1, s2;
read(s1,s2);
Map.insert({s1,s2});
arr[i] = s1;
}
if(n%2==1){
write(-1);
return;
}
int ans = n/2;
int x = 0;
FORR1(n){
if(arr[i]==Map[Map[arr[i]]]){
x++;
}
}
ans-=x/2;
write(ans);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int tc = 1;
//read(tc);
FOR(tc) {
//write("Case #", i+1, ": ");
solve();
}
}
Compilation message
polygon.cpp: In function 'int pmst(int)':
polygon.cpp:361:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
361 | for(int i = 0; i < adjlist[start].size(); i++){
| ~~^~~~~~~~~~~~~~~~~~~~~~~
polygon.cpp:369:23: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
369 | while(nodes.size()!=n){
| ~~~~~~~~~~~~^~~
polygon.cpp:128:49: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
128 | #define F_OR(i, a, b, s) for (int i=(a); (s)>0?i<(b):i>(b); i+=(s))
| ^
polygon.cpp:129:18: note: in expansion of macro 'F_OR'
129 | #define FORR1(e) F_OR(i, 0, e, 1)
| ^~~~
polygon.cpp:384:9: note: in expansion of macro 'FORR1'
384 | FORR1(adjlist[b].size()){
| ^~~~~
polygon.cpp: In function 'int query(vi, int)':
polygon.cpp:416:12: warning: value computed is not used [-Wunused-value]
416 | val-(1<<lsb(val));
| ~~~^~~~~~~~~~~~~~
polygon.cpp: In function 'bool gemacht(int, vi)':
polygon.cpp:448:1: warning: no return statement in function returning non-void [-Wreturn-type]
448 | }
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
364 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
251 ms |
16544 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
364 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
