N Coin Problem

Question:
Given a list of 'N' coins, their values being in an array A[], return the minimum number of coins required to sum to 'S' (you can use as many coins you want). If it's not possible to sum to 'S', return -1

For Example, input N coins array { 1, 3, 5 } and S as 11, the answer should be 3


My Answer:  (I am not sure if it is correct.)

int minCoins(int* a, int count, int target)
{
    int N = count;
    int S = target;

    int *mina=NULL;
    mina = new int[S+1];
 
    mina[0]=0;
     
    for(int i=1;i<=S;i++)
    {
        mina[i]=-1;
 
        for(int j=0;j<N;j++)
        {
            if(a[j]<=i && mina[i-a[j]] != -1)  
            {
                if(mina[i]==-1 || mina[i-a[j]]+1 < mina[i])
                {
                   mina[i] = mina[i-a[j]]+1;
                }
            }
        }
    }
 
    return mina[S];
}