一种求解图顶点染色的算法，从1号顶点开始染，依次维护其可用色链与不可用色链，当到某一点时没有可用色，则回退直到找到一种方案可使其正常染色，若退到开始

则染色失败，否则找到一种染色方案-One kind of solve the vertex coloring algorithm, starting from vertex 1 dye, in order to maintain its available color chain and not the use of color chain, to a certain point when the color is not available, then back up to find a solution to its normal coloring If the stain began to retreat failed, or to find a dye solution