why is this code gives run time error.
include
include
using namespace std;
int a[10000001];
string k;
int main() {
int t,i,j,n;
cin>>t;
while(t--){
cin>>k;
n = k.length();
int count = 0;
for(i = 0; i < n; i++){
a[i] = k[i] - '0';
if(a[i] == 9)
count++;
}
if(count == n){
cout<<1;
for(i = 1; i < n ;i++)
cout<<0;
cout<<1;
}
else{
bool check = false;
int mid = n/2;
i = mid - 1;
if(n%2 == 0)
j = mid;
else
j = mid + 1;
while(i >= 0 && a[i] == a[j]){
i--;
j++;
}
if(i < 0 || a[j] > a[i])
check = true;
while(i >= 0){
a[j] = a[i];
j++;
i--;
}
if(check){
int carry = 1;
if(n%2 == 1){
a[mid] += carry;
carry = a[mid]/10;
a[mid] %= 10;
}
i = mid - 1;
if(n%2 == 0)
j = mid;
else
j = mid + 1;
while(n >= 0){
a[i] += carry;
carry = a[i]/10;
a[i] %= 10;
a[j] = a[i];
j++;
i--;
}
}
for(i = 0; i < n; i++)
cout<<a[i];
}
cout<<endl;
}
return 0;
}