#include <iostream>
#include <algorithm>
#include <climits>
#include <cmath>
#include <map>
#include <set>
#include <bitset>
#include <iomanip>
#include <vector>
using namespace std;
static struct FastInput {
static constexpr int BUF_SIZE = 1 << 20;
char buf[BUF_SIZE];
size_t chars_read = 0;
size_t buf_pos = 0;
FILE *in = stdin;
char cur = 0;
inline char get_char() {
if (buf_pos >= chars_read) {
chars_read = fread(buf, 1, BUF_SIZE, in);
buf_pos = 0;
buf[0] = (chars_read == 0 ? -1 : buf[0]);
}
return cur = buf[buf_pos++];
}
inline void tie(int) {}
inline explicit operator bool() {
return cur != -1;
}
inline static bool is_blank(char c) {
return c <= ' ';
}
inline bool skip_blanks() {
while (is_blank(cur) && cur != -1) {
get_char();
}
return cur != -1;
}
inline FastInput& operator>>(char& c) {
skip_blanks();
c = cur;
return *this;
}
inline FastInput& operator>>(string& s) {
if (skip_blanks()) {
s.clear();
do {
s += cur;
} while (!is_blank(get_char()));
}
return *this;
}
template <typename T>
inline FastInput& read_integer(T& n) {
// unsafe, doesn't check that characters are actually digits
n = 0;
if (skip_blanks()) {
int sign = +1;
if (cur == '-') {
sign = -1;
get_char();
}
do {
n += n + (n << 3) + cur - '0';
} while (!is_blank(get_char()));
n *= sign;
}
return *this;
}
template <typename T>
inline typename enable_if<is_integral<T>::value, FastInput&>::type operator>>(T& n) {
return read_integer(n);
}
#if !defined(_WIN32) || defined(_WIN64)
inline FastInput& operator>>(__int128& n) {
return read_integer(n);
}
#endif
template <typename T>
inline typename enable_if<is_floating_point<T>::value, FastInput&>::type operator>>(T& n) {
// not sure if really fast, for compatibility only
n = 0;
if (skip_blanks()) {
string s;
(*this) >> s;
sscanf(s.c_str(), "%lf", &n);
}
return *this;
}
} fast_input;
#define cin fast_input
static struct FastOutput {
static constexpr int BUF_SIZE = 1 << 20;
char buf[BUF_SIZE];
size_t buf_pos = 0;
static constexpr int TMP_SIZE = 1 << 20;
char tmp[TMP_SIZE];
FILE *out = stdout;
inline void put_char(char c) {
buf[buf_pos++] = c;
if (buf_pos == BUF_SIZE) {
fwrite(buf, 1, buf_pos, out);
buf_pos = 0;
}
}
~FastOutput() {
fwrite(buf, 1, buf_pos, out);
}
inline FastOutput& operator<<(char c) {
put_char(c);
return *this;
}
inline FastOutput& operator<<(const char* s) {
while (*s) {
put_char(*s++);
}
return *this;
}
inline FastOutput& operator<<(const string& s) {
for (int i = 0; i < (int) s.size(); i++) {
put_char(s[i]);
}
return *this;
}
template <typename T>
inline char* integer_to_string(T n) {
// beware of TMP_SIZE
char* p = tmp + TMP_SIZE - 1;
if (n == 0) {
*--p = '0';
} else {
bool is_negative = false;
if (n < 0) {
is_negative = true;
n = -n;
}
while (n > 0) {
*--p = (char) ('0' + n % 10);
n /= 10;
}
if (is_negative) {
*--p = '-';
}
}
return p;
}
template <typename T>
inline typename enable_if<is_integral<T>::value, char*>::type stringify(T n) {
return integer_to_string(n);
}
#if !defined(_WIN32) || defined(_WIN64)
inline char* stringify(__int128 n) {
return integer_to_string(n);
}
#endif
template <typename T>
inline typename enable_if<is_floating_point<T>::value, char*>::type stringify(T n) {
sprintf(tmp, "%.17f", n);
return tmp;
}
template <typename T>
inline FastOutput& operator<<(const T& n) {
auto p = stringify(n);
for (; *p != 0; p++) {
put_char(*p);
}
return *this;
}
} fast_output;
#define cout fast_output
const int MAXN=1e5+1;
const int LG=17;
int** pa;
int *par,*h,*Up,*par1;
vector<int> ma[MAXN];
int get1(int& a)
{
return ((par1[a]==a)?a:par1[a]=get1(par1[a]));
}
void join1(int a,int b)
{
a=get1(a);
b=get1(b);
if(a!=b)
par1[a]=b;
}
int get(int& a)
{
return ((par[a]==a)?a:par[a]=get(par[a]));
}
bool join(int a,int b)
{
a=get(a);
b=get(b);
if(a!=b)
{
par[a]=b;
return 1;
}
return 0;
}
void dfs(int& x,int& p)
{
// cout<<x<<' '<<p<<endl;
pa[x][0]=p;
for(int j=1;j<LG;j++)
pa[x][j]=pa[pa[x][j-1]][j-1];
h[x]=h[p]+1;
for(auto y:ma[x])
if(y!=p)
dfs(y,x);
}
int lca(int x,int y)
{
if(h[x]>h[y])
swap(x,y);
for(int j=LG-1;j>=0;j--)
if(h[x]<=h[pa[y][j]])
y=pa[y][j];
if(x==y)
return x;
for(int j=LG-1;j>=0;j--)
if(pa[x][j]!=pa[y][j])
{
x=pa[x][j];
y=pa[y][j];
}
return pa[x][0];
}
void solve(int& x,int& p)
{
for(auto y:ma[x])
{
if(y!=p)
{
solve(y,x);
}
}
for(auto y:ma[x])
{
if(y!=p)
{
if(h[Up[x]]>h[Up[y]])
{
Up[x]=Up[y];
}
if(Up[y]==y)
{
cout<<x<<' '<<y<<'\n';
}
}
}
}
int main(){
ios::sync_with_stdio(false);
// cin.tie(NULL);
// cout.tie(NULL);
int n,m;
cin>>n>>m;
par=new int[n+1];
par1=new int[n+1];
h=new int[n+1];
Up=new int[n+1];
pa=new int*[n+1];
for(int i=1;i<=n;i++)
{
pa[i]=new int[LG];
par[i]=par1[i]=Up[i]=i;
}
for(int i=0;i<m;i++)
{
int x,y;
cin>>x>>y;
if(join(x,y))
{
// cout<<"Tree Edge "<<x<<' '<<y<<endl;
ma[x].push_back(y);
ma[y].push_back(x);
}
else
{
// cout<<"Cycle Edge "<<x<<' '<<y<<endl;
join1(x,y);
}
}
// cout<<"Tree Input:\n";
for(int i=1;i<=n;i++)
if(pa[i][0]==0)
dfs(i,i);
// cout<<"Cycle Input:"<<endl;
for(int y=1;y<=n;y++)
{
int x=get1(y);
// cout<<y<<' '<<x<<endl;
int c=lca(x,y);
if(h[Up[x]]>h[c])
{
Up[x]=c;
}
if(h[Up[y]]>h[c])
{
Up[y]=c;
}
}
// cout<<"Bridge Edges:\n";
for(int i=1;i<=n;i++)
if(pa[i][0]==i)
solve(i,i);
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
4696 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4700 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
5468 KB |
Output is correct |
| 2 |
Correct |
3 ms |
5464 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
26 ms |
11844 KB |
Output is correct |
| 2 |
Correct |
18 ms |
11356 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
38 ms |
16464 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
66 ms |
24936 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
121 ms |
35736 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
181 ms |
49420 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
229 ms |
62568 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
254 ms |
65536 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
299 ms |
65536 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
