src.cpp:3:31: error: size of array 'a' is too large
long long int c,n,a[1000000000],t;
^
src.cpp: In function 'int main()':
src.cpp:10:7: error: 'a' was not declared in this scope
cin>>a[i];
^
src.cpp:14:6: error: 'a' was not declared in this scope
if(a[i]<a[j])
^
src.cpp:19:8: error: 'a' was not declared in this scope
if(t+a[i]<c)
^