A linear time algorithm for L(2,1)-labeling of trees

Toru Hasunuma, Toshimasa Ishii, Hirotaka Ono +1

An L(2,1)-labeling of a graph $G$ is an assignment $f$ from the vertex set $V(G)$ to the set of nonnegative integers such that $|f(x)-f(y)|\ge 2$ if $x$ and $y$ are adjacent and $|…