POJ 3498 - March of the Penguins

Problem : Each vertex has a coordinate, p[i] animals and can burden q[i] jumps from it. Find all the vertex such that other animals all can jump to this vertex. The maximum jump distance is given.
Solution : Construct the Graph. Split each vertex to two vertices i and i'. i->i' has q[i] capacity. if i and j has distance within d, i'->j has inf capacity. source to each i has p[i] capacity. Now a vertex in original problem can be the destination t is equal to there is a edge from t to sink has capacity inf, and the flow can be maximum.
Hint : This problem is using highest-relabel to solve.