The 3-Coloring Problem There are two important observations to be noted, which generalize to all backtracking algorithms: (1)The nodes are generated in a depth-first-search manner. (2)There is no need to store the whole search tree;we only need to store the path from the root to the current active node.In fact,no physical nodes are generated at all;the whole tree is implicit.We only need to keep track of the color assignment.The 3-Coloring Problem There are two important observations to be noted, which generalize to all backtracking algorithms: (1) The nodes are generated in a depth-first-search manner. (2) There is no need to store the whole search tree; we only need to store the path from the root to the current active node. In fact, no physical nodes are generated at all; the whole tree is implicit. We only need to keep track of the color assignment