1710. Maximum Units on a Truck

class Solution {
    public int maximumUnits(int[][] boxTypes, int truckSize) 
    {
        int a[] = new int [1001];
        int s=0,i;
        for(i=0;i<boxTypes.length;i++)
        {
            a[boxTypes[i][1]]+=boxTypes[i][0];
        }
        for(i=1000;i>=0;i--)
        {
            if(a[i]==0)
                continue;
            if(truckSize>=a[i])
            {
                s+=(i*a[i]);
                truckSize-=a[i];
            }
            else
            {
                s+=(i*truckSize);
                break;
            }
        }
        return s;
    }
}