Language: C++

/*
PROG: apc001e
LANG: C++11
    _____
  .'     '.
 /  0   0  \
|     ^     |
|  \     /  |
 \  '---'  /
  '._____.'
 */
#include <bits/stdc++.h>

using namespace std;

long long readi()
{
	long long input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
	{
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = 10 * input + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	return input;
}
void printi(long long output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
string reads()
{
	string input = "";
	char c = ' ';
	while (c <= ' ')
	{
		c = getchar();
	}
	while (c > ' ')
	{
		input += c;
		c = getchar();
	}
	return input;
}
int sgn(long long x)
{
	if (x < 0) 
	{
		return -1;
	}
	if (x > 0) 
	{
		return 1;
	}
	return 0;
}
long long randomize(long long mod)
{
	return ((1 << 30) * rand() + (1 << 15) * rand() + rand()) % mod;
}

#define MP make_pair
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-20;

#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 100010

long long normalize(long long x, long long mod = INF)
{
	return (((x % mod) + mod) % mod);
}

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

int N;
vector<int> edge[MAXN];
int parent[MAXN];
int ans = 1;

void dfs_par(int u)
{
	for (int v : edge[u])
	{
		if (v == parent[u])
		{
			continue;
		}
		parent[v] = u;
		dfs_par(v);
	}
}

int32_t main()
{
	ios_base::sync_with_stdio(0); 
	srand(time(0));
	//	cout << fixed << setprecision(12);	
	//	cerr << fixed << setprecision(12);
	if (fopen("apc001e.in", "r"))
	{	
		freopen ("apc001e.in", "r", stdin);
		freopen ("apc001e.out", "w", stdout);
	}
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		int u, v;
		cin >> u >> v;
		edge[u].PB(v);
		edge[v].PB(u);
	}
	dfs_par(0);
	for (int i = 0; i < N; i++)
	{
		ans = max(ans, edge[i].size() - 1);
	}
	cout << ans << '\n';
	//	cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}


Compiler output:
a.cc: In function 'int32_t main()':
a.cc:169:26: error: no matching function for call to 'max(int&, std::vector<int>::size_type)'
  169 |                 ans = max(ans, edge[i].size() - 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:12:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:169:26: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'std::vector<int>::size_type' {aka 'long unsigned int'})
  169 |                 ans = max(ans, edge[i].size() - 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:169:26: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
  169 |                 ans = max(ans, edge[i].size() - 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~