1080B - Margarite and the best present.cpp

#include<bits/stdc++.h>
#define endl '\n'
#define ll long long int
#define loop(i,a,b)           for(ll i=a;i<=b;++i)
#define pb                    push_back
#define F                     first
#define S                     second
#define mp                    make_pair
#define clr(x)                x.clear()
#define MOD                   1000000007
#define itoc(c)               ((char)(((int)'0')+c))
#define vl                    vector<ll>
#define SZ(x)                 (x).size()
#define all(p)                p.begin(),p.end()
#define mid(s,e)              (s+(e-s)/2)
#define sv()                  ll t,n; scanf("%lld",&t);n=t; while(t--)
#define tcase()               ll t,n; cin>>t;n=t; while(t--)
#define iscn(num)             scanf("%d",&num);
#define scn(num)              scanf("%lld ",&num);
#define debug(n)              cout<<(n)<<endl;
using namespace std;
const ll INF = 2e18 + 99;
typedef pair<ll,ll> Pair;
typedef vector<ll> vec;
bool file=0,rt=1;
clock_t tStart ;
void FAST_IO();
////////////////////////

int main()
{

    FAST_IO();
    ////////////////////////
    ll n ; scn(n);
    while(n--){
        ll l, r; scn(l) ; scn(r);
        ll total = (r*(r+1))/2 ;
        ll temp = (l* (l-1))/2;
        total-=temp ;
        ll odd= r/2 ;
        if(r&1)
            odd++;
        odd= odd*odd ;
        odd-=((l/2)*(l/2));
        odd*=2;
        printf("%lld\n",total-odd);

    }
    

    ////////////////////////
    if(rt && file){
     printf("\nTime taken: %.6fs", (double)(clock() - tStart)/CLOCKS_PER_SEC);
    }
    return 0;
   }

void FAST_IO()
{
    // ios_base::sync_with_stdio(0);
    //cin.tie(NULL);
    //cout.tie(NULL);
    //cout.setf(ios::fixed);
    //cout.precision(2);
    if(rt && file){ tStart = clock(); }
    if(file){
    #ifndef _offline
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    }
}