Graph coloring algorithms generally use m-ary search trees, and the search strategy uses depth first. The constraint condition is that at node <x1, x2,…, xk>, the color used by the node in the adjacency list of vertex k+1 can no longer be used; if the node in the adjacency list has used m colors, then node k+ 1 Can not be colored, trace back from the node to its parent node.
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