Optimum Selection

We are given n items with labels from 1 to n . We are also given a special rooted tree with 1 as the root. At node number i in the special tree , a packet ( Pkt[i] ) having infinite number of items of label i is kept. A packet ‘Pkt[i]’ of items is defined by 2 parameters : a[i],b[i] The value of an item in the packet is a[i] . But the value of 'a[i]' keeps on reducing every time we take an item