Getting Segmentation Fault in Problem BUSYMAN

[arjitarora26]

SPOJ.com - Problem BUSYMAN

My code is working on the local machine , but i am getting segmentation fault. I am new to STL, can someone help me out please.

here is the code.

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define mp make_pair
#define f first
#define s second
#define pb push_back
bool comp(pair<ll,ll> a,pair<ll,ll> b){
if(a.s>b.s)
return false;
else
return true;

}
int main(){
ll t,n;
cin>>t;
ll count,last_time;
vector< pair<ll,ll> > v;
while(t–)
{

	v.clear();
	count=1;

	cin>>n;

	ll a,b;
	for(ll i=0;i<n;i++)
		{
			cin>>a>>b;
			v.pb( mp(a,b) );				
		}

	sort(v.begin(),v.end(),comp);

	last_time = v[0].s;
	for(ll i=1;i<n;i++)
		{
			if(v[i].f >= last_time)
			{
				count++;
				last_time = v[i].s;
			}
		}
	cout<<count<<endl;

}
}

Thanks.

[hodobox]

Hi! The problem is with the following

bool comp(pair<ll,ll> a,pair<ll,ll> b){
if(a.s>b.s)
return false;
else
return true; }

after changing it to

bool comp(pair<ll,ll> a,pair<ll,ll> b){
return a.s<b.s;}

your code gets accepted.

as far as I know (but feel free to do your own research), the reason for this is the way STL sort expects the comparator to work - your implementation returns true for two equal elements, mine returns false. The way STL interprets that afaik is ‘if A comp B is true, then A < B. if neither A comp B, nor B comp A, then it means A == B’. But yours returned true both times, as if A < B and B < A, and it cant cope with it.

hope this helps