can u guyz tell me whats wrong in my code?

long arrayManipulation(int n, vector> queries) {

long int arr[n+1];
memset(arr,0,sizeof(arr));
long int m = queries.size();
long int max = 0;
long int sum = 0;
for(int i=0;i<m;i++)
{
    long int a = queries[i][0];
    long int b = queries[i][1];
    long int k = queries[i][2];

    arr[a-1] += k;
    arr[b] -= k;
}
for(int x=0;x<n;x++)
{
    sum += arr[x];
    if(max < sum)
        max = sum;
}
return max;

}