Language: C++

#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(),i.rend()
#define rep0(i,j) for(lli i=0;i<j;i++)
#define rep1(i,j) for(lli i=1;i<=j;i++)
#define rep0d(i,j) for(lli i=j-1;i>=0;i--)
#define MAX 1000000007
typedef struct tree Tree;
 
using namespace std;
 
 
bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
	return left.first < right.first;
}
 
struct tree {
	queue<lli> leaf;
	lli num;
};
 
Tree t[200001];
 
void dfs(lli n, lli num) {
	t[n].num += num;
	while (!t[n].leaf.empty()) {
		dfs(t[n].leaf.front(), t[n].num);
		t[n].leaf.pop();
	}
 
}

Compiler output:
a.cc:12:11: error: 'pair' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |           ^~~~
a.cc:1:1: note: 'std::pair' is defined in header '<utility>'; this is probably fixable by adding '#include <utility>'
  +++ |+#include <utility>
    1 | #define all(i) i.begin(),i.end()
a.cc:12:16: error: 'lli' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                ^~~
a.cc:12:21: error: 'lli' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                     ^~~
a.cc:12:26: error: 'left' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                          ^~~~
a.cc:1:1: note: 'std::left' is defined in header '<ios>'; this is probably fixable by adding '#include <ios>'
  +++ |+#include <ios>
    1 | #define all(i) i.begin(),i.end()
a.cc:12:32: error: 'pair' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                                ^~~~
a.cc:12:32: note: 'std::pair' is defined in header '<utility>'; this is probably fixable by adding '#include <utility>'
a.cc:12:37: error: 'lli' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                                     ^~~
a.cc:12:42: error: 'lli' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                                          ^~~
a.cc:12:47: error: 'right' was not declared in this scope
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                                               ^~~~~
a.cc:12:47: note: 'std::right' is defined in header '<ios>'; this is probably fixable by adding '#include <ios>'
a.cc:12:52: error: expression list treated as compound expression in initializer [-fpermissive]
   12 | bool cmpf(pair<lli, lli> left, pair<lli, lli> right) {
      |                                                    ^
a.cc:17:9: error: 'queue' does not name a type
   17 |         queue<lli> leaf;
      |         ^~~~~
a.cc:18:9: error: 'lli' does not name a type
   18 |         lli num;
      |         ^~~
a.cc:23:6: error: variable or field 'dfs' declared void
   23 | void dfs(lli n, lli num) {
      |      ^~~
a.cc:23:10: error: 'lli' was not declared in this scope
   23 | void dfs(lli n, lli num) {
      |          ^~~
a.cc:23:17: error: 'lli' was not declared in this scope
   23 | void dfs(lli n, lli num) {
      |                 ^~~