View Compilation Error

0_0_25577050_26424.cpp:6:15: error: uninitialized const 'cnt' [-fpermissive]
 constexpr int cnt[MAXN];
               ^
0_0_25577050_26424.cpp: In function 'int main()':
0_0_25577050_26424.cpp:15:16: error: assignment of read-only location 'cnt[i]'
         cnt[i] = __builtin_popcount(i);
                ^