January 2022 enrollments are closed and the course commences on 8th of January, 2022. For future cohorts

LCPC12F Solution

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>

#define DEBUG 1

using namespace std;

#define ll long long
#define gc getchar_unlocked

void scanint(ll int &x)
{
register int c = getchar_unlocked();
x = 0;
int neg = 0;
for(;((c<48 || c>57) && c != '-');c = gc());
if(c=='-') {neg=1;c=gc();}
for(;c>47 && c<58;c = gc()) {x = (x<<1) + (x<<3) + c - 48;}
if(neg) x=-x;
}

int readline ( char * str ) {

int i = 0;
char ch;
while ( (ch=getchar()) != '\n' ) {
str[i++] = ch;
}
str[i] = '\0';
return i;
}

#define SIZE 2020

ll int hash[SIZE];

int main ( int argc , char * argv[] ) {

int t , z;
scanf("%d" , &t);
for ( z = 1 ; z <= t ; z++ ) {
ll int x , n;
scanint(x);
scanint(n);

for ( int i = 0 ; i < 2020 ; i++ )
hash[i] = 0;

ll int temp;
ll int count = 0;

for ( int i = 0 ; i < n ; i++ ) {
scanint(temp);

if ( x < temp )
continue;

count += ( hash[x-temp] );
hash[temp] ++;

}
printf("%d. %lld\n" , z,count);
}
return 0;
}